Where to add code to execute during registration

Hi there,

I’m wondering if someone might know where to add php code to registration.

I have the code already, I just would like to know which file and perhaps where it should be added to execute during registration.

Basically it adds some user data in the usermeta, I would like to execute it at the same time the new user hits the REGISTRATION BUTTON.

Any help would be very very much appreciated – THX =)

The code is below in case you need to know.

//______________________________________GET COOKIE START________________________________
	$user_refer = $_COOKIE['referrer'] ; //If user does not register now this will get the cookie info later
	if (empty($user_refer)) { //if cookie empty do nothing
	echo ''; }

	else  //if cookie has value do this

	//global $wpdb;
	$refer_metaid = get_usermeta($user_refer,'Refered');
	$points = get_usermeta($user_refer, POINTS);
	$new_user_info = get_userdatabylogin( $user_name );
	$new_user_id = $new_user_info->ID;

	$ref_points = 25; //amount of points from referring
	$refer_info = get_userdata($user_refer);
	$refer_username = $refer_info->user_login;

	update_usermeta($user_refer,'Refered',$refer_metaid . $user_name . '<br />');
	update_usermeta($new_user_id,'Sponsor',$refer_username);
    if ($points < 0) {
	  $points = 0;}
	update_usermeta($user_refer, POINTS, $points + $ref_points);
	//__________________________________________END OF GET COOKIE____________________________________