Embed the captcha image by calling a php script in "contact_us.php":
<img src="/image.php" width="60" height="20" alt="Please enter the values from this image" />Edit contact_us.php file and exactly after the below line:
if (isset($HTTP_GET_VARS['action']) && ($HTTP_GET_VARS['action'] == 'send')) {place the verification code:
// Captcha check
$t = trim($HTTP_POST_VARS['verify']);
if ($t == "") {
$captcha_error = "Enter the verification code!";
$error = true;
$messageStack->add('contact', $captcha_error);
} else if (trim($_SESSION["thecode"]) == "") {
$captcha_error = "No verification code generated!";
$error = true;
$messageStack->add('contact', $captcha_error);
} else if ($_SESSION["thecode"] != strtoupper($t)) {
$captcha_error = "Invalid verification code!";
$error = true;
$messageStack->add('contact', $captcha_error);
}
else
{ // End Captcha Check