Add Directory Links to the Menu

1) Add the Directory Link to the menu via Appearance > Menus > Custom Link
Set the URL to /directory/ with your choice of title.

Nettl :Directory - Add Directory Link to Menu

2) Add a Directory Category to the menu via Appearance > Menus > Directory Categories
Select the categories to add.

Nettl :Directory - Add Directory Category to Menu

An example of the Directory Category Renault:

Nettl Directory - Category Page

If you want help in this matter, please contact your local nettl studio.