Some so/so examples in http://search.cpan.org/dist/CGI-Ajax/MANIFEST, CGI::AJAX inside CGI::AJAX and http://www.linux-magazine.com/Magazine/Downloads/62/Perl/, http://www.linux-magazine.com/Issues/2006/62/Perl-AJAX, http://www.cgi-app.org/index.cgi?AjaxInfo and http://learn.jquery.com/

I say "so so" because they won't teach you how the internet works, how tcp/ip, sockets, websites, html, ajax, all fit together, but they are a start, they are short examples of one way to do it