Untitled

<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
        <form method="post" action="index.php">
        username:<br/>
        <input type="text" name="username"><br/>
        password:<br/>
        <input type = "password" name="password"><br/>
        <input type = "submit" value="Login!">
    </form>
<body>

</body>
</html>


<?php

    session_start();

    $username = "user";
    $password = "password";


    if (isset($_SESSION['Logged_in']) && $_SESSION['Logged_in'] == true){
        header("Location: sucess.php");
    }

    if ( isset($_POST['username']) && isset($_POST['password'])) {
        if($_POST['username'] == $username && $_POST['password'] == $password)
        {
            $_SESSION['Logged_in'] = true;
            header("Location: sucess.php");

        }
    }


?>