What exactly do you want to do? There are probably many answers to your question depending on your end goal.

If you just want a simple list of IPs and how they submitted myapp.cgi, then that job is usually done by the webserver. Check your logs. If the information is not in there, you can probably change your webserver's configuration to enable it.

If, on the other hand, you want to set up some kind of session, you probably want to use cookies and some kind of Perl module that handles the whole session thing for you like, oh, say, CGI::Session :)