how do i get this contact form to work for me

[Alter_Ego]

<?php
$contact_name = $_POST['name'];
$contact_email = $_POST['email'];
$contact_subject = $_POST['subject'];
$contact_message = $_POST['message'];

if( $contact_name == true )
{
   $sender = $contact_email;
   $receiver = "lynnsgetaway@ipasifika.net";
   $client_ip = $_SERVER['REMOTE_ADDR'];
   $email_body = "Name: $contact_name \nEmail: $sender \n\nSubject: $contact_subject \n\nMessage: \n\n$contact_message \n\nIP: $client_ip \n\nFlash Contact Form provided by http://www.flashmo.com";      
   $extra = "From: $sender\r\n" . "Reply-To: $sender \r\n" . "X-Mailer: PHP/" . phpversion();

   if( mail( $receiver, "Flash Contact Form - $contact_subject", $email_body, $extra ) )
   {
      echo "success=yes";
   }
   else
   {
      echo "success=no";
   }
}
?>