I don't know how this works either. This link looks like it might be helpful for those of us who need more information to get started.
http://freenode.net/using_the_network.shtml
These also:
http://dooyoo-uk.tripod.com/mirc/basicirc.htm
http://www.intracities.com/support/irc.html
http://www.usd.edu/trio/tut/start/irc.shtml
http://www.ker95.com/html/basics.html
http://www.irchelp.org/irchelp/irctutorial.html