I would suggest ReCaptcha:
http://recaptcha.net/
Adding that would be super easy.
To use the one you are using though, maybe something like...
Find:
PHP Code:
else{
//We are attempting to register the user...
//First MD5 hash the passwords:
$pass1 = md5($pass1);
$pass2 = md5($pass2);
Replace With:
PHP Code:
else{
//We are attempting to register the user...
include_once $_SERVER['DOCUMENT_ROOT'] . '/securimage/securimage.php';
$securimage = new Securimage();
//First MD5 hash the passwords:
$pass1 = md5($pass1);
$pass2 = md5($pass2);
Find:
PHP Code:
else if($tos != "yes"){
//User did not agree to TOS
$article_title = "Terms of Service Error";
$article_content = $notos;
}
Replace With:
PHP Code:
else if($tos != "yes"){
//User did not agree to TOS
$article_title = "Terms of Service Error";
$article_content = $notos;
}
else if($securimage->check($_POST['captcha_code']) == false){
// The captcha is wrong, put your message here...
$article_title = "Captcha Incorrect";
$article_content = "Captcha Incorrect";
}
Try that and see if it works. :)