How do I add WooCommerce products or product categories to a custom menu?
To add a product page or product category page to a custom menu, complete the following steps in your WordPress Admin Panel:
Go to Appearance > Menus
In the upper right corner, click on Screen Options and ensure the "Products" and "Product Categories" boxes are checked
If you only have one menu, then skip this step! If you have more than one menu on your website, use the drop down beside "Select a menu to edit:" to begin editing the correct menu.
There is a list of expandable sections on the left side of this page for things like Pages, Posts, and Blog Categories. If you completed step 2 correctly, you will also see Products and Product Categories in this list. If you click on them, they'll expand to show you a list of products (or product categories, depending on which you click).
Select the checkboxes beside the products or categories that you wish to add to the menu, then press the Add to Menu button. This will insert them into the Menu Structure shown on the right side of the page.
Drag and drop the newly added items into the menu positioning of your choice. If you wish for them to be submenu options, you can drag them slightly to the right under any existing menu option. They'll appear indented.
Press the blue Save Menu button
You should now see the product or product categories in the menu on your website.