For more indepth information about using CVS take a look here a this great manual about CVS. There is another great resource dedicated to CVSon the Devguy's website, and of course on the WinCvs site itself.
Two other sites that might be interesting: Info about the CVS-Concurrent Version System and CVS Best practices
Most information you'll find isn't written for WinCVS, but for command line CVS clients. That is no problem since WinCVS also has a command line window.