session_start();
//login page
if(mysql_num_rows($result) != '0'){ // If match.

        session_register("username"); // Craete session username.

        header("location:admin/admin.php"); // Re-direct to admin.php    
    exit;

    }else{ // If not match.

        $message="Please Incorrect your account !";

    }

/ / Sonra login başarıyla admin.php gitmek

session_start();

$ _SESSION ['username'] echo;