You've come this far, and now you're screaming for more! Where else can you go to learn more about all this stuff?
Try the following man pages, for starters:
For old-school actual hold-it-in-your-hand pulp paper books, try some of the following excellent guides. Note the prominent Amazon.com logo. What all this shameless commercialism means is that I basically get a kickback (Amazon.com store credit, actually) for selling these books through this guide. So if you're going to order one of these books anyway, why not send me a special thank you by starting your spree from one of the links, below.
Besides, more books for me might ultimately lead to more guides for you. ;-)
TCP/IP Network Administration by Craig Hunt. Published by O'Reilly & Associates, Inc. ISBN 1565923227.
Advanced Programming in the UNIX Environment by W. Richard Stevens. Published by Addison Wesley. ISBN 0201563177.
Using C on the UNIX System by David A. Curry. Published by O'Reilly & Associates, Inc. ISBN 0937175234. Out of print.
On the web:
BSD Sockets: A Quick And Dirty Primer (has other great Unix system programming info, too!)
Intro to TCP/IP (gopher)