Questions like this have been asked before:
http://www.antionline.com/showthread...&highlight=IRC
http://www.antionline.com/showthread...&highlight=IRC
http://www.antionline.com/showthread...&highlight=IRC
http://www.antionline.com/showthread...&highlight=IRC
http://www.antionline.com/showthread...&highlight=IRC

Anyways, you get the point.

I'm to busy now to write a tutorial on IRC, but if you did a search of the Tutorial Forums like moxnix suggested, you'll find lots of information.

As for IRC Client, if you're on Windows I suggest X-Chat, and if you're on Linux I suggested either X-Chat or Irssi.

Peace
MB