If you know nothing about TCP/IP, I'd start off with Douglas E. Comer's awesome book: TCP/IP Volume 1.
You don't need to read all of it, there's lots of useful stuff in there.
Once you've covered that, look at one of the several open source networking implementations, such as boost asio. IMHO this is the easiest networking library to get up and running. Once this has piqued your interest further, then start to investigate some of the lower level socket details. Btw, brumScouse already mentioned Beej's guide, this is also a very good resource.
And then when you are further along, and you want more: google C10K! ;)
