Joomla newbie module question

I'm being tasked with creating some modules for a joomla site but I have no experience with joomla (typical, right). Anyway I've got some time before defecation and oscillating device meet so I familiarizing myself with joomla. I was following the mod_helloworld tutorial available on the joomla site but the module is not showing up in the extensions manager. Any help/explanations would be appreciated.

This is what I did:

create a mod_hellworld directory in the modules directory, added a mod_helloworld.php, helper.php, mod_helloworld.xml, a tmpl directory and placed default.php file in there.

Here's the XML file.

<?xml version="1.0" encoding="utf-8"?>
<extension type="module" version="1.6.0" client="site" method="upgrade">
    <name>Hello World!</name>
    <author>Steve Suranie</author>
    <version开发者_如何学Go>1.6.0</version>
    <description>Simple Hello World module.</description>
    <files>
        <filename module="mod_helloworld">mod_helloworld.php</filename>
        <filename>mod_helloworld.xml</filename>
        <filename>index.html</filename>
        <filename>helper.php</filename>
        <filename>tmpl/default.php</filename>
        <filename>tmpl/index.html</filename>
    </files>
</extension>

mod_helloworld.php

<?php
  defined('_JEXEC') or die; // no direct access allowed

  require_once dirname(__FILE__).DS.'helper.php'; // get helper files

  $hello = modHelloWorldHelper::getHello($params);
  require JModuleHelper::getLayoutPath('mod_helloworld');
 ?>

helper.php

 <?php
class modHelloWorldHelper {
    /**
     * Retrieves the hello message
     *
     * @param array $params An object containing the module parameters
     * @access public
     */    
    function getHello( $params ) {
        return 'Hello, World!';
    }
}
?>

The module needs to registered in Joomla. Following are the ways to do it:

• Remove the folder from the modules directory. zip the files (using winzip for example). then upload & install it from joomla administration.
• Or, you can keep the folder in the modules directory and add an entry for this module in the database table 'jos_modules' (database prefix will be 'jos_' if you haven't changed it during installation)