Download an irc client such as mIRC if you don't already have one. Basic guide on using mIRC here: http://www.mirc.com/ircintro.html
1. Connect to host: irc.sythe.org, port: 6667
2. Find the "[IRC_TOKEN]" link on this page (change to nextgen lite if you can't see it.)
3. Click it, refresh the page, click it again, then copy the token string.
4. Use the token to log into IRCSythe by typing /login <token-string-here> after your IRC client connects. Your nick will be hard-set to your Sythe.org username and you can then use the server like any other IRC network.