Categories are essential, as they enable you to group equivalent products. This helps customers find their way through the variety of your catalog, and narrow down their search when looking for a specific type of product. Categories also make it easy for the customers to find and compare them (thanks to PrestaShop's product-comparison feature).
Once you have finished configuring your category, save it, and you are ready to fill it with products.
Navigating and editing categories
The "Edit" button in the button bar enables you to edit the parent category of the currently-displayed sub-categories. This means that when you are viewing the main sub-categories, clicking the "Edit" button will enable you to edit the "Home" category.
You can click on any category in the table: this will open that category, and display all of its sub-categories. In effect, this will change the context of the interface: clicking the "Edit" button will edit the current parent category, and clicking the "Add new" button will open the category creation form with the "Parents category" option set to the current parent category.
Importing and exporting categories
Besides the "Add new", the "Edit" and the usual "Help" buttons, the button bar also features two buttons:
More import options are available in the "CSV Import" page of the "Advanced parameters" menu.
Adding products to a category
In order to add a product in a category, you must open the product configuration page and go to its "Association" tab on the left. This is where you can set the categories to which the product belongs.