PHP script for submit buttons

I have a form that I want to use that doesn't go through a forwarding service. However I can't figure out how to get the PHP script to function. I've placed the HTML code for the form in an HTML only gallery and it works fine. I just can't get the PHP to kick in during the submission process.

Is PHP able to work in Smug Mug? If so, where do I place the script?

Thanks,

Eleni

http://eleni-collages.smugmug.com/