There's quite a bit more to modules, references, objects, and web programming than we can possibly hope to cover in this one small chapter. A whole book could be written on CGI programming. In fact, dozens have been. For your continued research into these matters, check out the following reference list:
The LWP library from CPAN
O'Reilly & Associates' CGI Programming on the World Wide Web by Shishir Gundavaram
O'Reilly & Associates' Web Client Programming with Perl by Clinton Wong
O'Reilly & Associates' HTML: The Definitive Guide, Second Edition 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 Programming in C and Perl, by Thomas Boutell