Board Thread:Clan Talk/@comment-75.83.11.201-20140728171735/@comment-25237169-20140728204408

You can't join a clan, really. You have to make one, or ask someone to invite you to one. You can invite someone to your clan by adding them as a friend while in a game, then pressing on the blue smiley face in the corner of the screen, next to your profile. Then, you press: Clan, and finally: Add. The list of your friends will then show up.

In order for this to work, the person you added has to accept your friend request.