The cgi-sys/FormMail.cgi is likely the form action. On submit, the form sends the data using the method provided (or get if no method is specified) to the script targeted by action. In this case, what appears to be a PERL script.
To create an interactive form that does something other than just presentation, you need to submit the data to a server processing language (such as PHP, perl, ASP/ASP.NET, JSP, python, etc, etc), and the server language processes the input and deals with it accordingly (storing in a database or file, emailing it, etc).
You may want to start here: http://php.net/manual/en/tutorial.forms.php
and then do a quick google search for php form submission tutorials. You'll likely find a wide variety that show how to submit data to a database or file storage as well as email.