How to override login page?

I followed https://www.drupal.org/node/350634#comment-10569550 tutorial

- I modified 'themes\bartik\template.php' adding function

function bartik_theme() {
$items = array();

$items['user_login'] = array(
'render element' => 'form',
'path' => drupal_get_path('theme', 'bartik') . '/templates',
'template' => 'user-login',
'preprocess functions' => array(
'bartik_preprocess_user_login'
)
...
return $items;
}

I created 'themes\bartik\templates\user-login.tpl.php' OR '\sites\all\theme\bartik\templates\user-login.tpl.php' OR ''\sites\all\themes\bartik\templates\user-login.tpl.php'

But it does not work. Nothing happens.