There are also a number of pre-written freeware/shareware scripts that can be bought/used that you can then modify. This is a great way to "wet your feet" in Perl. You can start at:

CGI Resources
Free Perl Code
Hot Scripts
CGI Directory

I'm sure there are more, but you should be able to find something starting with these.

Please read some of the warnings on PerlMonks concerning these boiler-plate scripts in terms of security, efficiency, etc.

Also take careful note of any copyright issues.

Also try:

Finding scripts
Finding secure scripts