Adding a Custom Menu Fields I am new to Drupal and I am trying to create a menu (top navigation links) where a small description would be visible under the main Title.

I am trying to replicate this sites menu.

Is there any module that would allow me to do this? Or is there something I missing that would allow the Description that you type to show up the way I am looking for. Any help with this would be greatly appreciated!!
You can do this with theme_menu_link().

A menu item's description is by default output as a tooltip (ie, in the title attribute).  Here's a thread that shows how to do take advantage of that using hook_menu_link() to achieve more or less the result you want.