A good client program to start with is mIRC (just search for it, or go to mIRC.com).
Once installed, it will ask you for your name, desired handle, and give you a list of servers to pick from. Make sure it’s a Newnet server. It ought to say something like “Newnet: US, WA, Seattle” or similar. Then click ‘connect’.
From there it’ll do it’s thing, and all you need to do is type in the channel to join: “#straightdope”. The pound sign indicates a channel.
IRC is like any other place on the Internet. As long as you don’t accept file transfer requests from people you don’t know or piss people off, you’re generally safe. I’ve been doing this for about 10 years now, and have never had a problem.
Thanks for the flashback folks, I used to host/run a server on Newnet, had no idea it still existed, since you know, everything springs into existence when I arrive and dissolves into dust when I leave.