Mostly tips on the socket stuff. I'm pretty sure I can figure out most of the rest on my own. For example, do I need a program running on my server for the sockets, and how would I do this stuff?

Most MUDs set up a daemon which listens for connections. That's only half of the issue, though: you need to figure out how to listen for connections and process the game world with sufficiently low latency that your users don't crucify you upside-down by your :-) for creating something terribly slow. There's a few methods that you can employ to achieve this: forking, threads, and various non-forking models. Reading (and especially playing with the code in) perlipc is highly recommended required. If you can afford a book on the subject, I highly recommend Lincoln Stein's Network Programming with Perl. While not published by the Perl standby, O'Reilly, it's still worth the money.