PrestaShop 1.7.x. How to create a category and assign it to the top menu

1. In your PrestaShop admin panel go to Catalog -> Categories section: 
2. Click the Add new category button to create a new category: 
3. In the appeared window, fill in the information about the category and save it.
4. A newly created category will appear in the list of available categories: 
5. To assign a category to the menu, go to Modules -> Modules and Services section. Choose the Installed modules tab. Find TM Mega Menu module and click the Configure button: 
6. Click on the Add item tab or “+” button to create a new item: 
7. Set the following options. In the Link drop-down choose the Existing URL option and choose your Test category among the list below it: 
8. Click the Save button. Refresh your website. Now, your new category appears in the main menu.

Hopefully, this tutorial was helpful for you.