Sending my form using my ISP Smtp

[crazylegseddie]

im sure this is a novice problem and ive found it hard to find similar sources that integrate with my form. All i want to do is link my form to send to my specified email using my ISP smtp. PS. The form is not hosted using my ISP. Here is the code:

<?php
$firstname=$_POST['FirstName'];
$lastname=$_POST['LastName'];
$email=$_POST['Email'];
$comment=$_POST['Comment'];

$toaddress = 'myemail@hotmail.com';
$subject = 'You Have A New Comment';
$mailcontent = 'First Name: '.$firstname. "\n"
.'Last Name: '.$lastname. "\n"
.'Email: '.$email. "\n"
.'Comments: '.$comment. "\n";

$fromaddress = 'From: sales@mydomain.com';

mail($toaddress, $subject, $mailcontent, $fromaddress);


?>

if anyone could help me incorporate my ISP smtp here I would greatly appreciate your help. Ive also tried PHPMailer and unable to get that to work :( Thank You for your time.