First step would be to get a client.
Let’s assume these people are using windows, they are probably better off getting mirc.
www.mirc.com (most commonly used windows client)
Install, setup nickname and some other stuff that’s fairly easy (I'll find a how-to in a moment)
Then connect to irc.bp6.com
Then join the #bp6 channel.
That’s a basic explanation. I'll go find a how-to on the web now.