For modules, get the CGI or LWP modules from CPAN. For textbooks, see the two especially dedicated to web stuff in the question on books. For problems and questions related to the web, like ``Why do I get 500 Errors'' or ``Why doesn't it run from the browser right when it runs fine on the command line'', see the troubleshooting guides and references in perlfaq9 or in the CGI MetaFAQ:
http://www.perl.org/CGI_MetaFAQ.html