As hinted at before, there is a lot more information on CVS than could reasonably be covered here. Hopefully the material presented here is sufficient to give anyone a solid understanding of the basics, and get them started managing their first project with CVS. But for those of you yearning to deepen your knowledge...
The primary source for all things CVS is the CVS website at http://www.cvshome.org/. It contains links to documentation, tutorials, accessory programs, etc. It also has an online HTML version of the full CVS manual.
Jim Blandy's Introduction to CVS is also available at the above site, and provides a very thorough walk-through of a typical CVS session, including an example of how CVS handles textual conflicts. Highly recommended.
For more immediate information, start with the cvs man page (by issuing the command ``man cvs''). There are other CVS-related man pages, which you may discover under the ``SEE ALSO'' section of the CVS man page.
The full CVS manual, referenced throughout this document, is available on the PCSE system in GNU Info format, and may be accessed by invoking ``info cvs''. The info documentation reader is a more complex documentation system than the man pages, but well worth learning. After invoking info, you can type ``h'' to take the info tutorial.
For more information on RCS, the direct ancestor to CVS, visit the CVS website and do a Site Search on ``RCS''. This will bring up a description of RCS and its relationship to CVS, as well as links to other sources of RCS information.
If you want to get really involved with using CVS, the book Open
Source Development with CVS by Karl Fogel is available in most major
bookstores. You can also access many of the chapters online at
http://cvsbook.red-bean.com/.