for this you would want to create a categopries and subcategories table:
categoryID - primary key
subcategoryID - primary Key
subcategoryCategoryID releates to categories.categoryID
then in the produtcts table, relate the product to the subcategory using the subcategoryID value.
creating the menu this way is very similar to the tutorial.
for the main level, set it to use the categoryID as the ID.
the second level should use the subcategoryID as the ID
in the filtering section set it to filter using the subcategoryCategoryID as the nesting column.
next, for the products menu, use the productID as the key column, in the filtering section, use the productSubCategoryID column as the nesting column.