There are probably (most assuredly) some simple networking components built in to VB. You can probably get some for free off the internet, if not.
One in particular I would recommend that is easy for beginners to learn, that I know has VB support is IPWorks (http://www.dev-soft.com). You can download a "trial" version of their components for free. (The trial versions pop-up annoying nag screens when you open a socket).
You could use their IPPort and IPDaemon components to setup a TCP connection and have one machine keep track of the ball position and tell the other where it is, and its velocity, while the other tells the server it''s paddle position (when it changes).
There are probably also DirectPlay VB components you could use, too.
You could use the Winsock control which comes with all VB versions (at least I think it does). It''s really easy to work with and shouldn''t bring you much trouble. I also believe there are some good examples on how to use it in MSDN.