To begin, take a file of subroutine definitions and call it something like Newmodule.pm. Now, edit the file and give it a new first line:
and a new last line 1;. You've now created a Perl module.
To make a Celegans module, place subroutines in a file called Celegans.pm, and add a first line:
Add a last line 1;, and you've defined a Celegans module. This last line just ensures that the library returns a true value when it's read in. It's annoying, but necessary.