There's quite a bit more to modules, references, objects, and web developing than we can possibly hope to cover in this one small chapter. A whole tutorial could be written on CGI developing. In fact, dozens have been. For your continued research into these matters, check out the following reference list:

CGI.pm docs
The LWP library from CPAN
Anonymous' CGI Developing on the World Wide Web by Shishir Gundavaram
Anonymous' Web Client Developing with Perl by Clinton Wong
Anonymous' HTML tutorial, Second version by Chuck Musciano and Bill Kennedy
Addison-Wesley's How to Setup and Maintain a Web Site by Lincoln Stein, M.D., Ph.D.
Addison-Wesley's CGI Developing in C and Perl, by Thomas Boutell
Nick Kew's CGI FAQ
Manpages: perltoot, perlref, perlmod, perlobj

Further Reading