IRC stands for internet relay chat. It was one of the first hugely successful ways of gathering with other like-minded people on the internet in the 90's for chatting in real-time. It is also still used behind the scenes with some of the chat systems available today (battle.net, twitch.tv).
Many free ice clients exist today for Windows and other operating systems. The one I use is called ice chat (can be downloaded from cnet, I did so earlier today)
You'll want to add a server (select EFnet, then random EFnet server). Once connected to the server you can join the channel by typing /join #vandweller at the server's command line prompt. There is probably some way to use the graphical interface to do this but I like the old-school way of typing commands.
If done correctly you will be in the #vandweller channel on the EFnet network. Give it a shot!