Refer this article for more help : http://www.proudengineers.com/using-php-to-send-email/ You can use the fields from contact field to get the email address and send mail accordingly.
I like the easy way myself and I've found the easiest way yet and for free too, my favorite price. It's open source so you can use it anywhere as well. The setup is a doddle, just go to: http://phpfmg.sourceforge.net and make one, then copy 'n paste the code or iframe it into a page. I've used it on both my sig sites.
<?php $to = "someone@example.com"; $subject = "Test mail"; $message = "Hello! This is a simple email message."; $from = "someonelse@example.com"; $headers = "From:" . $from; mail($to,$subject,$message,$headers); echo "Mail Sent."; ?> Code (markup):