Java version! I just remembered that there’s a java version of the nighstar chat, so you don’t have to download anything. (Er, sorry I didn’t think of this earlier.)
Just go here: http://www.nightstar.net/110.0.html
Then enter a name in the nickname field. You can ignore the password field, you don’t really need one. Type “#Windstone” in the channel field, and then hit the connect button.
The only downside there is that if there’s some problem with connecting, I’m less likely to be able to help you, because I don’t use the java myself, so I’m not as familiar with it. And it’s only good for nightstar, you can’t get onto any other irc networks with it. But it’s a lot simpler, I know, and will get you into the exact same chatroom as the longer set of instructions for getting mIRC will.