Have you started any Network coding yet? I posted a basic udp chat system in the code archives, it uses the same port for both machines for sending and recieving, but I think it gives a good idea of how to set up the basic features needed to pass information in a client/ server setup.
Heres the code archive post...
http://www.blitzbasic.com/codearcs/codearcs.php?code=2261
Heres the code archive post...
http://www.blitzbasic.com/codearcs/codearcs.php?code=2261