In the demo version Main menu is located here:
![](https://nkdev.info/wp-content/uploads/2020/10/main-menu-1-1024x632.png)
To add or change a Main Menu, go to the Appearance → Menus
Then you can select a menu to edit or create a new menu:
![](https://nkdev.info/wp-content/uploads/2020/10/main-menu-2.png)
If the Main menu you need is not in the list, just create a new one:
![](https://nkdev.info/wp-content/uploads/2020/10/main-menu-3.png)
Then tie the new menu to the Main Menu area:
![](https://nkdev.info/wp-content/uploads/2020/10/main-menu-4.png)
Then you can add menu items. More details about this you can read here: https://en.support.wordpress.com/menus/