The way this script is supposed to work is as follows: The first time you access the URL, it displays a form. When you submit the form, the script gets called a second time, passing along your form data and displaying it.

By capturing the output of the first run as HTML, you've created a "snapshot" of the first run's output. But when you click submit nothing happens, because the HTML is not a script.

In simple terms, a web server does one of two things:
1. if you request a file from inside the html directory, it just gives it to you. It's up to your browser to parse and render any html markup the file may contain.
2. if you request a file from inside the cgi-bin directory, the web server runs the file and delivers the output (if any) to your browser.

So, short answer: you put the output of your script in the html directory when what you need to do is put your script in the cgi-bin directory.