How do I set my clan tag in Starcraft 2?

I've tried looking for official faqs, forums, etc. I know how to create/join a clan but I can't find any proper instructions to get my battletag to display something like:

<clan_name> battletag

I'm sorry if the answer to this is incredibly obvious but I've tried to change both in game and on Battlenet's website and I cannot figure out how to do this for the life of me despite seeing various people with their own clan tag.

Solution 1:

From the information I have gathered and summarized from this thread it goes like this:

From the opening screen of the game, bottom right hand corner, down by where your friends list is, there's a second button for Groups/Clans. You can create one from there.

This might means you have made a group not a clan. Do the following to make it a clan

Login, main screen, groups chat, create, on the dropdown, click "clan" instead of leaving it on "group"