Bugwamp's right, you don't need to do anything in order to make a clan. You just need to think of a name, and start to recruit people. There's a forum here dedicated to player matchup (http://www.rpgforums.net/forumdisplay.php?f=31) which you can use to either recruit people, or join other people's clans (if you want).
That metal monkey moderator guy is just the operator of the channel. For example, if you have the name Alemon on bnet, and you join the channel "Op Alemon", you'll become the moderator (with the metal hammer).
This'll let you moderate the channel, by banning people, and what not. You'll also be able to designate people (people who'll become moderator when you leave the channel). For more information about Chat room moderator commands, check out http://www.battle.net/info/commands.shtml and look under the heading Chat Room Operator Commands