CGI is very useful if you want users to submit any information to you or if you want to store info without cookies. Your server must be able to process CGI files in whatever language you use to write it. The most popular language and my preference is CGI, but C++ can be used among others. The following links are for perl only.
- Webmonkey CGI - This is made to be just an intro to CGI, but it is still a pretty good one.
- CGI Tutorial - This is a pretty decent CGI tutorial adapted from a book and partially online.
- Learn By Example - If you see something you would like to able to do view source and figure it out.
- Google - If you want to know how to do something search google for the solution.