WordPress.org

1. Upload the entire jquery-drop-down-menu-plugin folder to the /wp-content/plugins/ directory.
2. Activate the plugin through the 'Plugins' menu in WordPress.
3. Add <?php jquery_drop_down_menu('HOME') ?> function on your theme header.php or where you want to display menu.

You will find 'Dropdown Menu' menu in your WordPress admin panel.

Under 'Dropdown Menu' you will see number of Settings

* Multi-level dropdown
* Exclude Pages
* Include Custom menu
* Two type Jquery Animation
* Option to enable/disable Jquery Animation
* Page Sorting Setting
* Page Sorting Order
* Depth

For basic usage, you can also have a look at the plugin homepage.