Contact Form problem

HEY GUYS, PLEASE HELP ME OUT. I GOT THE CONTACT FORM PHP FILE FROM HERE(http://www.kirupa.com/web/code/contact_form.zip)AND I PUT IT ON MY WEB SITE, ([url=“http://www.BUDHIRAJA.NET.QA/CONTACT.HTM”]WWW.BUDHIRAJA.NET.QA/CONTACT.HTMAND)) AND WHENEVER I CLICK SUBMIT, INSTEAD OF SENDING THE MAIL, IT DOWNLOADS THE PHP FILE. PLEASE TELL ME WHAT TO DO!!! PLEASE!!