Posting variables with php

my php code is as follows:

<?php
$sendTo = "[email protected]";
$subject = “Info”;

$headers = "From: " . $_POST[“firstname”];
$headers .= “<” . $_POST[“email”] . ">
";
$headers .= "Reply-To: " . $_POST[“email”] . "
";
$headers .= "Return-Path: " . $_POST[“email”];
$message = $_POST[“referalmethod”];
$message = $_POST[“message”];

mail($sendTo, $subject, $message, $headers);
?>

I need to send about 10 more variables with this in addition to the 2 that are listed here:

“referalmethod”
“message”

the only one that arrives in the email is “message”

how do I get the others to post in the body of the sent email message?

THX