Form Page:
<html>
<head>
<title></title>
</head>
<body>
<form method="post" action="coupon.php">
<input type="text" name="name" />
<input type="text" name="email" />
<input type="submit">
</form>
</form>
</body>
</html>
coupon.php
<?php
if(isset($_POST['name'] && $_POST['name'] != '')){
$name = $_POST['name'];
}
if(isset($_POST['email'] && $_POST['email'] != '')){
$email = $_POST['email'];
}
// Create your coupon, and where you want the name and email to appear in the coupon, you just echo your variables you created above.
echo $name."<br />";
echo $email;
?>
Obviously, you'd need to build in a lot more error checking, and this is very very very basic, but it will give you an idea of how and where to begin.
Your second page would need to have the *.php extension in order for it to be parsed via PHP.