Please click on Catalog Manager now.
NOTE: Any information that is entered during setup can be changed or removed at any time.

The first page that loads is the Departments page which is shown below. Your store is organized into departments and subdepartments for navigation. Each store starts with one department (named Storefront) and you can add as many departments under Storefront as you need. Each department can have subdepartments below it. And any department can have products to buy displayed on the page.

Click Add Department where the red arrow is shown.

The next screen is the Edit Department page. Enter in " T-Shirts " as your department name and then select "Department" from the Display Template area and press update where the red arrow points.

Your previous page should now reload with the new department/category shown where the red arrow points.

Press Update and click next on this guide