If your new to the world of the IRC then you can start by using Rizon's webchat.
This is a simple webchat that'll get the job done and has some neat features along with it. If you don't have any reason to be on Rizon and you don't know where to go just yet, try #chat. If you ever need help with IRC/Rizon only, try asking in #help.
In the case that you use a client like mIRC, irssi, or XChat...
Connect to irc.rizon.net using ports 6660-6670 and 7000 for standard connections, or 6697/9999 for SSL connections.