Adding drop down shop category menu with woocommerce

Hi … I’m using building a website for my daughter using woocommerce and a ‘woo-friendly’ very flexible theme so in theory I shouldn’t have to write any PHP (although I know that language very well). I’ve created a hierarchy of woocommerce product categories (two deep) and would like to have this under a ‘shop’ item on the main nav bar (which uses the WP main menu and Appearance->Menus to create it). I can build this menu item by item using the Product Categories sidebar but I’m sure that there must be a simple way of building the menu structure automatically from the Woocommerce product hierarchy. I see that there is a Woocommerce Categories Menu plugin (I have it installed and actiavted) which suggests that it does what I want but I just can’t see how to use it to add the product categories automatically to the menu.

I’m sure that I’m just being more than a bit dense here. Can anyone enlighten me please ?

Thanks
Ron