ReCaptcha For Newbies - recaptcha

Question

I've got ReCaptcha working but despite reading the documentation and the answers posted here, I'm still at a loss for setting up the server side. My HTML form calls <form id="contactForm" class="well" method="POST" action="php/contactform.php">.
What and where do I place the server-side recaptcha in this file? (I meant it when I titled this newbie. I really need explicit instructions):
<?php
if($_POST){
// response hash
$response = array('message'=>'');
}
try {
// Get values from form
$name=$_POST['cname'];
$email=$_POST['cemail'];
$subject=$_POST['csubject'];
$message=$_POST['cmessage'];
$formcontent="From: $name \n Email: $email \n Subject: $subject \n: $message";
$recipient = "rabbidubrow#fivegates.org";
$subject = "KHF Contact Form";
$mailheader = "From: $email \r\n";
$send_contact=mail($recipient, $subject, $formcontent, $mailheader) or die("Error!");
// let's assume everything is ok, setup successful response
$response['type'] = 'success';
$response['message'] = 'Thank you! We will be in touch shortly.';
} catch(Exception $e){
$response['type'] = 'error';
$response['message'] = $e->getMessage();
}
// now we are ready to turn this hash into JSON
print json_encode($response);
exit;
?>

Answer 1

You will need
1. Include your recaptcha.php
2. Declare your private and public keys
3. Check for POST of your captcha. If it success, give a response, if it fails, catch the exception.
Below is one of my scripts that was done up for your reference.
require_once('assets/config/recaptchalib.php');
$publickey = "xxxx";
$privatekey = "xxxxx";
if ($_POST["recaptcha_response_field"]) {
$resp = recaptcha_check_answer ($privatekey, $_SERVER["REMOTE_ADDR"], $_POST["recaptcha_challenge_field"], $_POST["recaptcha_response_field"]);
if ($resp->is_valid) {
$continue = true;
}
}