Hi, and welcome to LQ
IRC = Internet relay chat
How to use depends on what you chose, and
(to a certain extent) what is running on the server
you're connection to.
http://freshmeat.net/search/?q=%2BIR...&Go.x=0&Go.y=0
should give you plenty to chose from :)
Cheers,
Tink
P.S.: The thread title is somewhat misleading :)