How to customize Contact form template

Hi,
I can't find the PHP file that styles the "Contact form" template (that includes google map, contact informations and contact form). Where I can find it or how can I customize that template?
Thanks


P.S. The contact form doesn't work. I get always error "Field ...... is required" for each fields!

Ok, it's feedback.php

but the contact form doesn't work. I tried to substitute it with Contact form 7 plugin but it's the same!

I solved this issue placing the contact form 7 before the map.