Here is a quick tutorial...
To log onto the server, there are a number of tools you can use. My personal favorite is Chatzilla, a free application which comes with Mozilla.
If you download Mozilla from mozilla.org and install the complete version, Chatzilla will be on your computer. Open Mozilla, and go to the tools menu and select Chatzilla. A new window will open.
In the text space for the "client" tab, type:
A new tab will open that welcomes you to the server. Then type:
Another tab will open up. You should see my name there with a green dot next to it. Then start chatting!
Another client that can be used on Windows is trillian from trillian.cc. On Linux, xchat is a nice client.
However, a google search for IRC and Windows or whatever OS you happen to be using should bring up quite a few other tools.