Помогите я не могу сделать окно авторизации чтоб она работала.

<?php
session_start();
require('connect.php');
if(isset($_POST['username']) and isset($_POST['password'])){
$username=$_POST['username'];
$password=$_POST['password'];
$qveri="SELECT * FROM users WHERE username='$username' and password='$password' ";
$result= mysqli_query($connection,$qveri) or die (mysqli_error($connection));
$cout= mysqli_num_rows($result);
if($cout==1){$_SESSION['username']=$username;} else {$fmsg="Ошибка";}
}

<?php
$connection = mysqli_connect( $host="localhost", $user="root", $password="");
$select_db=mysqli_select_db($connection,'имя_бд');
?>