What do you want to do:

• Create a new CVSHOME
• Check out an existing project
• Update an existing project
• Add a file to an existing project
• Remove a file from an existing project
• Commit all changes
• Tag an existing project for release
• Import existing source code into a new module
• Branch an existing project
• Merge to existing branches
• Triggering on various events

Version Management with CVS (Per Cederqvist et al.): http://www.network-theory.co.uk/docs/cvsmanual/index.html
Another nice link about CVS in general (in Danish) http://www.daimi.au.dk/~eriksoe/cvs.html