Tutorial
To Add the Drop Down Menu the first step is to enable the category to have a drop down menu, and the second step is manually adding the departments to the drop down menu.
A. Enable the Category
1. From the control panel choose 'Edit Category' and select the category from the drop down menu

2. In the field 'Show Category as Drop Down Menu in Top Nav Panel?' choose to show on the site's pages.

3. Press the Apply Changes button at the bottom of the page
B. Set the Departments to Show
1. From the control panel choose 'Edit Department'

2. In the field 'Show Department Link in Top Nav Panel?' choose to show on the site's pages.

3. Press the Apply Changes button at the bottom of the page
NOTE: The category will only show in the top nav bar if there is at least ONE DEPARTMENT set to show on the top nav panel.