That is not a free perl "course". It's a very basic perl/cgi intoduction. Not a very good one but not too bad either. More thorough perl intro here:
Beginning Perl - perl.org
and some more free online books on that same site:
The perl.org Online Library - perl.org
also lots of perl info here:
Perl 5.8.8 documentation - perldoc.perl.org
it's the best resource for up-to-date perl documentation and includes tutorials, FAQs, and more.