Usergroup Changes

[webkinztowncom]

I have made a contact form. I know people have wrote articles on things like a php code to send a PM without a modification. I want it so if someone submits the contact form (clicks button) that it changes them to a different usergroup.

Is this possible? If so, what is the code?

-EDIT

Here is the link to the auto-pm php code...
https://vborg.vbsupport.ru/showthread.php?t=82786