Design templates are a list of the template which you prepare for users to select on their end They can add them to a product with one click.
To manage Templates, just go to Admin panel > Templates. In this page, you can see the thumbnail of templates, name, categories and some filter options on the top as well.
By default, it will show all items here. You can refine the list to show only specific templates by using the drop-down menus above the items list. The list auto refresh after you make a selection.
When you set a price for Template, It will show up on Customer end.
It's also counted to price of the product