From the side navigation, Click on the "Product and Services" menu. This will expand the sub-menu items.
From the sub-menu items, click on the "Category List" sub-menu.
Then you need to click on the "Add new category" button. Lets add "Clothing" and "Shoe" categories. Once you have added the categories, you will see the "Number of Category(s)" and "Active Department(s)" have changed from 0 to 2, as we added 2 categories.