can't see my help link under operations!!

Hello, i have begin implementing my first module named first and after installing it in my /sites/default/modules and enabling it, i can't see my help link under admin/modules tab : operations
Here is my code
first.info
---------

;$Id$

name = First
description = A first module.
package = Drupal 7 Development
core = 7.x
php = 5.3
files[] = first.module

first.module
--------------
<?php
// $Id$
/**
* @file
* A module exemplifying Drupal coding practices and APIs.
*
* This module provides a block that lists all of the
* installed modules. It illustrates coding standards,
* practices, and API use for Drupal 7.
*/
/**
* Implements hook_help().
*/
function first_help($path, $arg) {
if ($path == 'admin/help#first') {
return t('A demonstration module.');
}
}

please tell me where is my error