Here's a list of free IRC clients: http://en.wikipedia.org/wiki/List_of_IRC_clients
Once it's installed just go to Tools>!ChatZilla. Type (or copy and paste):
/server irc.prospers.org 6667
Hit enter and wait a minute (it seems to be a slow server) for messages to scroll by. Type
Once you've set it up, you can set it to automatically log you in whenever you start it up if you like.