<?php

$user = 'admin';
$pass = 'passwd';

if($_SERVER['PHP_AUTH_USER'] != $user || $_SERVER['PHP_AUTH_PW'] != $pass)
{
   header('WWW-Authenticate: Basic realm="Amiya Secret Area"');
   header('HTTP/1.0 401 Unauthorized');
   exit;
}

?>

Reszta po autoryzacji :D