Using Form to Call PHP Script

Help!!!

I’ve been scouring this forum and Google for half a day and I give up!

I essentially want to have a contact form on a page and when you press “Submit”, to call a script.php somewhere. I do not want php code to execute when the page loads (like an echo, ext) I want to use a form to post variables to a php script and then use mail().

Can anyone explain how to do this?????
I’ve tried:
Placing the code in the page template.
Getting various plugins exec-php, ext.

It always says it cannot find the script.

All I want to do is run a mail script.