I'm just a beginner with PHP. I created a PHP login system. Now I want to echo the username to the logged in user on the index.php page.
Here's the code I have so far. It would be great if someone could suggest a way of doing this. Thanks!

index.php
Code:
<?php
session_start();
require_once 'classes/Membership.php';
$membership = new Membership();

// If the user clicks the "Log Out" link on the index page.
if(isset($_GET['status']) && $_GET['status'] == 'loggedout') {
	$membership->log_User_Out();
}

// Did the user enter a password/username and click submit?
if($_POST && !empty($_POST['username']) && !empty($_POST['pwd'])) {
	$response = $membership->validate_User($_POST['username'], $_POST['pwd']);
}
														
?>


<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Login</title>
<link rel="stylesheet" type="text/css" href="css/default.css" />
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.1/jquery.min.js"></script>
<script type="text/javascript" src="js/main.js"></script>
</head>

<body>
<div id="login">
	<form method="post" action="">
    	<h2>Login <small>enter your credentials</small></h2>
        <p>
        	<label for="username">Username: </label>
            <input type="text" name="username" />
        </p>
        
        <p>
        	<label for="pwd">Password: </label>
            <input type="password" name="pwd" />
        </p>
        
        <p>
        	<input type="submit" id="submit" value="Login" name="submit" />
        </p>
    </form>
    <?php if(isset($response)) echo "<h4 class='alert'>" . $response . "</h4>"; ?>
</div><!--end login-->
</body>
</html>
index.php (the page that the user is redirected to after logging in)
Code:
<?php
require_once 'classes/Membership.php';
$membership = New Membership();

$membership->confirm_Member();	

?>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<link rel="stylesheet" href="css/default.css" />

<!--[if lt IE 7]>
<script type="text/javascript" src="js/DD_belatedPNG_0.0.7a-min.js"></script>
<![endif]-->


<title>Untitled Document</title>



</head>

<body>

<div id="container">
	<p>
    	You have logged in.
    </p>
    <a href="login.php?status=loggedout">Log Out</a>
</div><!--end container-->

</body>
</html>
membership.php
Code:
<?php

require 'Mysql.php';

class Membership {
	
	function validate_user($un, $pwd) {
		$mysql = New Mysql();
		$ensure_credentials = $mysql->verify_Username_and_Pass($un, md5($pwd));
		
		if($ensure_credentials) {
			$_SESSION['status'] = 'authorized';
			header("location: index.php");
		} else return "Please enter a correct username and password";
		
	} 
	
	function log_User_Out() {
		if(isset($_SESSION['status'])) {
			unset($_SESSION['status']);
			
			if(isset($_COOKIE[session_name()])) 
				setcookie(session_name(), '', time() - 1000);
				session_destroy();
		}
	}
	
	function confirm_Member() {
		session_start();
		if($_SESSION['status'] !='authorized') header("location: login.php");
	}
	
}
mysql.php
Code:
<?php

require_once 'includes/constants.php';

class Mysql {
	private $conn;
	
	function __construct() {
		$this->conn = new mysqli(DB_SERVER, DB_USER, DB_PASSWORD, DB_NAME) or 
					  die('There was a problem connecting to the database.');
	}
	
	function verify_Username_and_Pass($un, $pwd) {
				
		$query = "SELECT *
				FROM users
				WHERE username = ? AND password = ?
				LIMIT 1";
				
		if($stmt = $this->conn->prepare($query)) {
			$stmt->bind_param('ss', $un, $pwd);
			$stmt->execute();
			
			if($stmt->fetch()) {
				$stmt->close();
				return true;
			}
		}
		
	}
}
Thanks a lot!