Prestashop基本模块，小调整

I created file mymodule.php for Prestashop 1.4

<?php
if (!defined('_CAN_LOAD_FILES_'))
    exit;

class MyModule extends Module
{
    function __construct()
    {
        $this->name = "mymodule";
        $this->version = "1.0";
        $this->author = "Tomtop";
        $this->tab = "front_office_features";

        $this->_postErrors = array();

        parent::__construct();

        $this->displayName = $this->l("My Module Name");
        $this->description = $this->l("This is my module description.");
    }

    protected function setConfig($key,$value)
    {
        return Configuration::updateValue($this->name.$key,$value,true);
    }

    protected function getConfig($value)
    {
        return Configuration::get($this->name.$value);
    }

    protected function deleteConfig($value)
    {
        return Configuration::deleteByName($this->name.$value);
    }

    function install()
    {
        if (!parent::install()
            OR !$this->registerHook('home')
            OR !$this->registerHook('footer')
        )
            return false;
        return true;
    }

    public function uninstall()
    {
        parent::uninstall();

        return true;
    }


    public function hookHome($params)
    {       

    }

    public function hookfooter($params)
    {       

    }


    private function _postProcess()
    {
        $this->_html .= '<div class="conf confirm">'.$this->l("Updated")."</div>";
    }

    public function getContent()
    {
        $this->_html .= "<h2>".$this->displayName."</h2>";

        if (Tools::isSubmit("submit"))
        {   
            $this->_postProcess();
        }

        $this->_displayForm();

        return $this->_html;
    }   

    private function _displayForm()
    {   
        $this->_html .= '<form action="'.$_SERVER['REQUEST_URI'].'" method="post">

            <fieldset>
                <legend><img src="../modules/scroller/logo.gif" alt="" class="middle" />'.$this->l('Settings').'</legend>

                <br />
                <center><input type="submit" name="submit" value="'.$this->l('Upgrade').'" class="button" /></center>
            </fieldset> 
        </form>';
    }
}

Where in above code should be added mymodule.tpl template, which contain main html code, i.e.

return $this->display(__FILE__, 'mymodule.tpl');

Also, in which place in mymodule.php to add js and css files that are linked in head tag like this:

public function hookHeader()
{
    Tools::addJS($this->_path.'js/myjscript1.js');
    Tools::addJS($this->_path.'js/myjscript2.js');
    Tools::addCSS($this->_path.'css/mymodule.css', 'all');
}

And where should be added global $smarty; if it required in above code?

The hookHeader should be declared in the install method.

You should reference global $smarty at the beginning of each class method that needs to use $smarty.

That means that in the methods where you'll be using $this->display() to render a .tpl you should also add the global $smarty to be able to use the $smarty->assign() method.

Anything returned by the functions hookHome() and hookFooter() will be displayed when the hook points are rendered. Ignoring smarty to begin with you can just do something like:

public function hookHome($params)
{
  return "<h2>Wow, my module displays something</h2>";
}

You may of course want to use a template file with your module -- although you don't have to. If you are going to use a smarty template then you can declare a global instance within the hook functions.

public function hookHome($params)
{
  global $smarty;
  ...
  ...

As noted in Mihai's answer you will also have to modify the install function should you want to insert the css and js using the "header" hook:

function install()
{
    if (!parent::install()
        OR !$this->registerHook('home')
        OR !$this->registerHook('footer')
        OR !$this->registerHook('header')
    )
        return false;
    return true;
}