login_proses.php

<?php

//lu connect dulu, terus kalo udah copas code dibawah ini

$username = $_POST['username'];
$password = md5($_POST['password']);
$login    = mysqli_query($connect, "select * from nama_tabel_akunnya where nama_kolom_username='$username' and nama_kolom_password='$password'");
$result   = mysqli_num_rows($login);
if($result>0){
	//kalo berhasil kode ini yang di run
    $user = mysqli_fetch_array($login);
    session_start();
    $_SESSION['username'] = $user['username'];
    header("location:index.php");
}else{
	//kalo gagal kembali ke halaman login
    header("location:login.php");
}

?>