how to create submenus in drupal 7 - drupal-7

Question

I have a module that adds a link to main menu. When I click on that link the requested page gets loaded (a .js and .html file).
My main menu looks like this:
My link
My code looks like this:
<?php
/**
* Implements hook_menu()
*/
function kl_menu(){
$items = array();
$items['simple_link'] = array(
'title' => t('my link'),
'page callback' => 'build_page',
'access arguments' => array('access content'),
'menu_name' => 'main-menu',
'type' => MENU_NORMAL_ITEM,
);
/*
* build_page
*/
function build_page() {
drupal_add_js(drupal_get_path('module', 'kl') . '/mypage.js', 'file');
return ( file_get_contents( drupal_get_path('module', 'kl').'/mypage.html') );
}
Now I would like add a submenu instead of a simple plain link so that my main menu would look like this:
My submenu
my sublink1
my sublink2
I would like that when I click on "my submenu" then this sub menu expands displaying more links. Then when I reclick on my submenu I would like it to collapse.
I am pretty new to drupal php etc.
How can I acheive that. I am using garland theme.
Thanks
baba

Answer 1

/**
* Implements hook_menu().
*/
function kl_menu() {
$items['simple_link'] = array(
'title' => t('my link'),
'page callback' => 'kl_build_page',
'access arguments' => array('access content'),
'menu_name' => 'main-menu',
'type' => MENU_NORMAL_ITEM,
);
$items['simple_link/my_sublink_1'] = array(
'title' => t('my sub link 1'),
'page callback' => 'mymodule_sub_page_1',
'access arguments' => array('access content'),
'type' => MENU_NORMAL_ITEM,
);
$items['simple_link/my_sublink_2'] = array(
'title' => t('my sub link 2'),
'page callback' => 'mymodule_sub_page_1',
'access arguments' => array('access content'),
'type' => MENU_NORMAL_ITEM,
);
return $items;
}
/**
* Implements hook_theme().
*/
function kl_theme() {
$template_path = drupal_get_path('module', 'kl') . '/templates';
return array(
// File would be <module path>/templates/kl-build-page.tpl.php
'kl_build_page' => array(
'path' => $template_path,
'template' => 'kl-build-page')
),
// File would be <module path>/templates/kl-sub-page-1.tpl.php
'sub_page_1' => array(
'path' => $template_path,
'template' => 'kl-sub-page-1')
),
// File would be <module path>/templates/kl-sub-page-2.tpl.php
'sub_page_2' => array(
'path' => $template_path,
'template' => 'kl-sub-page-2')
),
);
}
/**
* Callback for main build page.
*/
function kl_build_page() {
drupal_add_js(drupal_get_path('module', 'kl') . '/mypage.js', 'file');
return theme('kl_build_page');
}
/**
* Page callback for sub page 1
*/
function kl_sub_page_1() {
return theme('kl_sub_page_1');
}
/**
* Page callback for sub page 2
*/
function kl_sub_page_2() {
return theme('kl_sub_page_2');
}