Wie kan mij helpen met mijn script van registreren en database?

<?php
$connect_error = 'Sorry, we\'re experiencing connection problems.';
mysql_connect('localhost', 'GEBRUIKERSNAAM', 'WACHTWOORD') or die($connect_error);
mysql_select_db('lr') or die($connect_error);
?>

<?php
function email($to, $subject, $body) {
	mail($to, $subject, $body, 'From: JE EMAIL INVULLEN ');
}

function logged_in_redirect() {
	if (logged_in() === true) {
		header('Location: index.php');
		exit();
	}
}

function protect_page() {
	if (logged_in() === false) {
		header('Location: protected.php');
		exit();
	}
}

function admin_protect() {
	global $user_data;
	if (has_access($user_data['user_id'], 1) === false) {
		header('Location: index.php');
		exit();
	}
}

function array_sanitize(&$item) {
	$item = htmlentities(strip_tags(mysql_real_escape_string($item)));
}

function sanitize($data) {
	return htmlentities(strip_tags(mysql_real_escape_string($data)));
}

function output_errors($errors) {
	return '<ul><li>' . implode('</li><li>', $errors) . '</li></ul>';
}
?>

<?php
function change_profile_image($user_id, $file_temp, $file_extn) {
	$file_path = 'images/profile/' . substr(md5(time()), 0, 10) . '.' . $file_extn;
	move_uploaded_file($file_temp, $file_path);
	mysql_query("UPDATE `users` SET `profile` = '" . mysql_real_escape_string($file_path) . "' WHERE `user_id` = " . (int)$user_id);
}

function mail_users($subject, $body) {
	$query = mysql_query("SELECT `email`, `first_name` FROM `users` WHERE `allow_email` = 1");
	while (($row = mysql_fetch_assoc($query)) !== false) {
		email($row['email'], $subject, "Hello " . $row['first_name'] . ",\n\n" . $body);
	}
}

function has_access($user_id, $type) {
	$user_id 	= (int)$user_id;
	$type 		= (int)$type;
	
	return (mysql_result(mysql_query("SELECT COUNT(`user_id`) FROM `users` WHERE `user_id` = $user_id AND `type` = $type"), 0) == 1) ? true : false;
}

function recover($mode, $email) {
	$mode 		= sanitize($mode);
	$email		= sanitize($email);
	
	$user_data 	= user_data(user_id_from_email($email), 'user_id', 'first_name', 'username');
	
	if ($mode == 'username') {
		email($email, 'U gebruikersaam', "Hallo " . $user_data['first_name'] . ",\n\nU gebruikersnaam is : " . $user_data['username'] . "\n\n-moffia.nl");
	} else if ($mode == 'password') {
		$generated_password = substr(md5(rand(999, 999999)), 0, 8);
		change_password($user_data['user_id'], $generated_password);
		
		update_user($user_data['user_id'], array('password_recover' => '1'));
		
		email($email, 'U wachtwoord is veranderd', "Hello " . $user_data['first_name'] . ",\n\nU nieuwe wachtwoord is: " . $generated_password . "\n\n-moffia.nl");
	}
}

function update_user($user_id, $update_data) {
	$update = array();
	array_walk($update_data, 'array_sanitize');
	
	foreach($update_data as $field=>$data) {
		$update[] = '`' . $field . '` = \'' . $data . '\'';
	}
	
	mysql_query("UPDATE `users` SET " . implode(', ', $update) . " WHERE `user_id` = $user_id");
}

function activate($email, $email_code) {
	$email 		= mysql_real_escape_string($email);
	$email_code = mysql_real_escape_string($email_code);
	
	if (mysql_result(mysql_query("SELECT COUNT(`user_id`) FROM `users` WHERE `email` = '$email' AND `email_code` = '$email_code' AND `active` = 0"), 0) == 1) {
		mysql_query("UPDATE `users` SET `active` = 1 WHERE `email` = '$email'");
		return true;
	} else {
		return false;
	}
}

function change_password($user_id, $password) {
	$user_id = (int)$user_id;
	$password = md5($password);
	
	mysql_query("UPDATE `users` SET `password` = '$password', `password_recover` = 0 WHERE `user_id` = $user_id");
}

function register_user($register_data) {
	array_walk($register_data, 'array_sanitize');
	$register_data['password'] = md5($register_data['password']);
	
	$fields = '`' . implode('`, `', array_keys($register_data)) . '`';
	$data = '\'' . implode('\', \'', $register_data) . '\'';
	
	mysql_query("INSERT INTO `users` ($fields) VALUES ($data)");
	email($register_data['email'], 'Activeer uw account', "Hallo " . $register_data['first_name'] . ",\n\nJe moet je account nog acitiveren met de onderstaande link:\n\nVULHIER JE WEBISTE IN  MET DE MAP WAAR JE  HEBT STAAN activate.php?email=" . $register_data['email'] . "&email_code=" . $register_data['email_code'] . "\n\n - moffia.nl");
}

function user_count() {
	return mysql_result(mysql_query("SELECT COUNT(`user_id`) FROM `users` WHERE `active` = 1"), 0);
}

function user_data($user_id) {
	$data = array();
	$user_id = (int)$user_id;
	
	$func_num_args = func_num_args();
	$func_get_args = func_get_args();
	
	if ($func_num_args > 1) {
		unset($func_get_args[0]);
		
		$fields = '`' . implode('`, `', $func_get_args) . '`';
		$data = mysql_fetch_assoc(mysql_query("SELECT $fields FROM `users` WHERE `user_id` = $user_id"));
		
		return $data;
	}
}

function logged_in() {
	return (isset($_SESSION['user_id'])) ? true : false;
}

function user_exists($username) {
	$username = sanitize($username);
	return (mysql_result(mysql_query("SELECT COUNT(`user_id`) FROM `users` WHERE `username` = '$username'"), 0) == 1) ? true : false;
}

function email_exists($email) {
	$email = sanitize($email);
	return (mysql_result(mysql_query("SELECT COUNT(`user_id`) FROM `users` WHERE `email` = '$email'"), 0) == 1) ? true : false;
}

function user_active($username) {
	$username = sanitize($username);
	return (mysql_result(mysql_query("SELECT COUNT(`user_id`) FROM `users` WHERE `username` = '$username' AND `active` = 1"), 0) == 1) ? true : false;
}

function user_id_from_username($username) {
	$username = sanitize($username);
	return mysql_result(mysql_query("SELECT `user_id` FROM `users` WHERE `username` = '$username'"), 0, 'user_id');
}

function user_id_from_email($email) {
	$email = sanitize($email);
	return mysql_result(mysql_query("SELECT `user_id` FROM `users` WHERE `email` = '$email'"), 0, 'user_id');
}

function login($username, $password) {
	$user_id = user_id_from_username($username);
	
	$username = sanitize($username);
	$password = md5($password);
	
	return (mysql_result(mysql_query("SELECT COUNT(`user_id`) FROM `users` WHERE `username` = '$username' AND `password` = '$password'"), 0) == 1) ? $user_id : false;
}
?>

<?php
session_start();
//error_reporting(0);

require 'database/connect.php';
require 'functions/general.php';
require 'functions/users.php';

$current_file = explode('/', $_SERVER['SCRIPT_NAME']);
$current_file = end($current_file);

if (logged_in() === true) {
	$session_user_id = $_SESSION['user_id'];
	$user_data = user_data($session_user_id, 'user_id', 'username', 'password', 'first_name', 'last_name', 'email', 'password_recover', 'type', 'allow_email', 'profile');
	if (user_active($user_data['username']) === false) {
		session_destroy();
		header('Location: index.php');
		exit();
	}
	if ($current_file !== 'changepassword.php' && $user_data['password_recover'] == 1) {
		header('Location: changepassword.php?force');
		exit();
	}
}

$errors = array();
?>

/* Resets */
ul {
	padding:0;
	margin:0 0 20px 0;
	list-style:none;
}

h1, h2 {
	padding:0;
	margin:0 0 20px 0;
	font-weight:normal;
}

p {
	padding:0;
	margin:0 0 20px 0;
}

a:link, a:visited {
	text-decoration:underline;
	color:#000;
}

a:hover {
	text-decoration:none;
}

ul li {
	padding:5px 0;
}

ul li input[type="text"], ul li input[type="password"] {
	width:200px;
}

textarea {
	width:400px;
	height:150px;
}

/* Headers */
h1 {
	font-size:1.8em;
}

h2 {
	font-size:1.4em;
}

.logo {
	font:2em Arial;
	margin:0 0 10px 0;
	padding:0;
	width:200px;
	color:#fff;
}

/* Containers */
body {
	background:lightslategray;
	font-family:Arial;
	font-size:0.8em;
}

#container, footer {
	background:#fff;
	width:920px;
	margin:0 auto;
	padding:20px;
}

header {
	width:940px;
	padding:10px;
	margin:0 auto 10px auto;
}

#container {
	min-height:500px;
	border-radius:5px 5px 0 0;
}

footer {
	border-radius:0 0 5px 5px;
}

.widget {
	margin-bottom:20px;
}

.widget h2 {
	margin:0 0 10px 0;
	padding:0 5px;
	font-weight:normal;
	border-bottom:1px solid #ddd;
}

.widget .inner {
	margin:0 10px;
}

/* Navigation */
nav {
	float:left;
}

nav ul {
	margin:0;
}

nav ul li {
	display:inline;
	margin-right:10px;
}

nav ul li a {
	text-decoration:none;
}

nav ul li.current {
	font-weight:bold;
}

nav ul li a.last {
	border-right:0;
}

/* Aside */
aside {
	width:260px;
	float:right;
	border-left:1px dashed #aaa;
	padding-left:15px;
}

.profile {
	background:#f9f9f9;
	border:1px dashed #ccc;
	padding:5px;
}

.profile img {
	width:100%;
}

/* Login */
#login li.link {
	margin-top:5px;
}

/* Footer */
footer {
	border-top:1px dashed #ddd;
	color:#999;
}

/* Misc */
.clear {
	clear:both;
}