So, you're wondering what Flickr is and how to use it? Maybe you've seen a lot of cool LEGO stuff on there and want to join in? No problem. In this guide, we'll go through the basic usages of the site and set you up in a nice position to start exploring the LEGO community there. Hang tight!
Simply put, Flickr is a photo sharing service that greatly emphasizes the community. It can become an integral part of your own photographic workflow, an important channel to communicate with fellow LEGO builders, or just a great source for inspiration, feedback and friendships. It started out as an independent website and was later acquired by Yahoo.
With Flickr, you can upload photos and share them. The site allows users to comment on each photo with the comments feature, or add notes directly on the pictures. It makes organizing things a breeze, with a powerful organizer, tags, sets and collections. You may join groups and send photos to them based on the interests of the groups; you can moderate who can see and comment on your photos with varied privacy settings, and much more.
To understand Flickr's role in the LEGO community one should know some AFOL history. Here goes a brief (perhaps slightly dramatized) version:
Once upon a time the Adult LEGO community was small and just. We hung out at LUGNET, where we discussed pictures hosted on Brickshelf. This was the way it had been done since we discovered each other on the 'net, and surely the way it would always be done. Everyone danced on green plains and talked with sugarcoated words.
But, trouble brewed. The community grew slightly larger. LUGNET couldn't keep up: it was clunky and horrible to use, the king and queen had deserted their people, and the plains withered soon after. So the community deserted the once green land, building niche forums of their own. It was the time of the great Exodus, and it left LUGNET dry. A few loyalists shouted in the dark before they, too, left. (Legend has it some people still visit, but it's probably just the ghosts of the past whispering about grand days of yore.)
Anyway, people where happy for a while. They talked in these new niche forums about their niche images that they still hosted on Brickshelf. There even sprung up a service to complement Brickshelf - MOCPages - where you could create a presentation for your images and get comments on them. Pretty neat.
But trouble brewed again. The community grew even larger. New people joined, and they had shorter attention spans and weren't willing to put up with clunky interfaces. And to be honest, neither wanted the old AFOLs. They all began to make demands of Brickshelf. "Make it easier to upload stuff!" they cried. Kargador Lochley, who ran the image hosting site, didn't want to. "You guys should be happy that I even do this!" he said. "Look, now I take it down for a few days so you'll see how bad it is without!" he said.
The community was terrified and didn't know what to do. But when all seemed lost, a small scouting party came back with golden tales about a new, promised land called Flickr. So everyone left and hasn't looked back since. Now they don't have to put up with crazy demands from Kargador or clunky interfaces. And all is well... for now.
Basically, the LEGO community is divided into three image hosting services these days: MOCPages, Flickr and Brickshelf. Flickr is the only one that isn't LEGO exclusive, but despite that it's probably the largest. MOCPages often attracts a younger audience and Brickshelf is but a shell of what it once was.
Discussions are also divided into many places. We have forums like FBTB, Classic-Castle, Classic-Space, Eurobricks and Builder's Lounge. But in addition to these sites a lot of the discussion has moved to flickr - the social tools on the site has essentially assimilated a lot of the community.
Sounds difficult to get a grasp of? It can be pretty tricky to navigate the LEGO community, but for now it's enough to know this: many people host their LEGO images on flickr. A lot of discussion is held on flickr. Begin there, get to know people and then branch out.
Flickr has two different memberships: a free service and the PRO account. The PRO account sets you back 24.95 per year. The free membership is limiting several features of flickr. The free version grants you (at the time of this writing) 100mb of upload capabilities per month where each photo can be 5mb. This is total uploads; uploading then deleting a photo will still count towards your upload limit. You may show up to 200 photos at a time (any above this number are then invisible to others). You may join and send photos to up to 10 different groups, and while you can upload large photos, only the resized versions will be available.
The PRO account offers quite a bit more. You receive unlimited upload capabilities, though individual photos are limited to 10mb each. You have unlimited groups, sets, collections, bandwidth, and storage. The high-def version of each of your photos is stored in its original form. You have the ability to replace photos, you may join up to 60 groups, and you get ad-free browsing. For a full comparison have a look at the flickr faq.
If you decide that you want to try flickr you'll have to sign up. The process is simple and fast. First and foremost, you’ll need a Yahoo! account. The name you choose here is not the same as your display name on flickr. When you go to the flickr page, you’ll click on the “Create Your Account” button on the right hand side. This will take you to the flickr/Yahoo! sign in page, where you’ll need to create a new Yahoo! id. This will take just a few minutes. After that, you’re good to go!

So you decided to give Flickr a go? Awesome! You can upload photos in a number of ways. I'll show you how to upload photos using the web interface.
If you go to the main flickr page after logging in, press the big link called Upload Photos to get started on your photo sharing adventure. You can also click Upload from the drop-down menu after clicking You in the top menu.

Click the link, and you'll be taken to the upload page. Follow the guidelines and make sure your pictures aren't too large. Flickr's usability is pretty great, so just do what says on the screen: start by clicking on the upload button, select the files you want to upload, select to whom you want to show the photographs and continue on by clicking on the pink Upload photos and videos button. Done. Your pictures are now on flickr.
Now would be a good time to add some meta data to your nice pictures, so it's not a bad idea to follow flickr's add a description-link.

At the top you'll find batch operations for all of your uploaded pictures. Choose to add tags to all of them or place them all in a set. Below that you can edit the title, description or tag of the individual image. You can change any of these aspects later in the future at any time, so don't worry. Just click save, and your pictures will appear in your photostream.
Not that hard, right? But to make it even easier, the flickr team has created a few more ways to upload just in case. Explore them and use the one you like the best.
Flickr comes with a handy tool called the Organizr. (Theory: the flickr teams 'e' button is broken.) The Organizr is easy to find - clicking Organize & Create in the main menu takes you to it. With it you can easily add tags, edit titles and descriptions, put photos in sets and collections and more. It’s all really intuitive, but if you want to know how it works I’d recommend reading the Flickr Organizr FAQ.

Tags are keywords that you give your pictures. The beauty of them is that tags are searchable both globally and locally. That is, you can find a specific tag both from ALL Flickr users or a specific tag from just one Flickr user. You can use as many tags as you wish. Separate different tags with a space, and write tags of several words "encapsulated between double quotes".
Sets are basically folders with pictures in them. Again, a free account is limited to creating two sets while pro accounts can create as many sets as there are pieces in HMS Hood. It's not a bad idea to create a new set for every model you upload, and a specific set for WIPs and tablescraps.
Collections are only available to pro users, and are as the name indicates collections of other collections or sets (not both). Think of them as a way to mimic your computer file structure: several folders within folders to create structure. Here’s an example of collections and sets used in tandem to organize Lego pictures.
Once you've organized your pictures into sets you can create slide shows that you can place on your site. Navigate to a set or tag and locate the slideshow button in the top right corner. This creates a slideshow that'll open in full screen. If you press the share button you'll be able to grab the embed code.
Flickr wouldn't be flickr without the great community. Adding people as contacts will enable you to view their photos at a later time (similar to a bookmark) and keep track of new photos as your contacts post them. Additionally, being listed as a contact by others may allow you to comment on or add notes to their photos.
The easiest way to add a contact is to locate their buddy icon. Simply click the drop down arrow next to their icon, and then select Add [name] as a contact?. It's really that simple. Once you mark someone as a contact, flickr will send them a flickrmail (flickr's private messaging system) to notify them, and the individual has the option of adding you as a contact as well. Be sure to check your flickrmail every now and then to see if people add you as a contact so you can check out their photos too. You'll find your flickrmail by clicking the little envelope in the upper-right corner.

The easiest way to find people is to start browsing photos. If you find someone who has interesting pictures, add them as a contact to subscribe to their photographs. If you want to find other LEGO people it's not a bad idea to identify a few key players and check out their contact list. I've done this in three genres: LEGO, low-key photography and character illustration. The result is a constant stream of inspiration and even friends - I've met many of my contacts in real life after we've learned a lot from one another on flickr.
Everyone you mark as a contact will become just that: a contact. You can also designate an individual as a friend or family. These settings are essentially different privacy settings - remember the uploader where you could select to mark a photograph as visible to friends or family? They're just different contact groups.
To keep track of your contacts and to see what they're posting, all you need to do is navigate to your contacts page. Here you can view the most recent pictures of your contacts. At the bottom, you can opt to see either the most recent picture from each contact or five of their pics. You can have a maximum of 3000 contacts, which should last you a while.
One of the best ways to explore photos and connect with people is to join and post photos to groups. Any flickr member can start a group, so there are many for you to choose from, each different from the next. The easiest way to start is by opening the Groups menu item in flickr's primary menu. There you can search for a group, start a new one, or - if you're already in a few groups - see them or view their recent activity.

If you're in none, start by searching for a few keywords that you're interested in. That should bring up a few interesting groups to check out. Some are open for anyone to join, others you need to request an invitation, and other still are private and doesn't show up in the search at all. A few key factors to look at when you consider joining a group are:
Hang around for a while and get a feel for the group. If you like the photos and the people there, join in! Talk to the people there, comment on their photos and discuss in the boards and you'll learn plenty. And who knows, you might even make a friend in the process!
You can find more groups by checking out Swooshable Buzz or Michael Huffman's BrickBuildr.
You've only just begun scratching the surface of flickr. There is much more to learn - create things with your photos, place them on a map, view statistics, and much more. See flickr's own tour, and then explore, learn, and enjoy it all yourself! Begin uploading pictures, talk to people and just have fun!
But yeah, it gets even better. Flickr will never run out of features: many people and organisations have put together tools of their own that interact with flickr's API. There are heck of a lot of things to explore out there, but the things below should be a good start.
And with that, I leave you. If you want to be my contact, I'm Bohman. See you on flickr!