IRC Chatzilla Help

Hey so I know this sounds ridiculous, but I dont really know how to use IRC. I always use AIM and gchat. Anyway I have the person I want to chat withs IRC number, how do I connect to them? I figured out the command /join and then whatever room to enter that room, but I just have their IRC number. Can anyone help? If there is a better IRC chat client I should be using let me know, but u should also know Im on a mac. Thanks you guys.

You sure he doesn't want to chat on icq rather then irc? I've never heard of someone having an irc number before.

wow wealthy I cant believe my foolishness. Thanks, ill try and figure it out now. Ive signed up with ICQ again never used it.