Hello yohanes,
you can add your restaurant menus images. You have to install woocommerce plugin first.

* If you have to add restaurant menus category then
you have to Go to Dashboard >> Products >> Categories
1. add Your restaurant menu name
2. select image & click on “add new category” button

Here is documentation link:
https://luzuk.com/demo/lz-restaurant/documentation/assets/images/category-product1.png
https://luzuk.com/demo/lz-restaurant/documentation/assets/images/category-product2.png
https://luzuk.com/demo/lz-restaurant/documentation/assets/images/category-product3.png

* If you have to add restaurant menus then
you have to Go to Dashboard >> Products >> click on “add new” button
1. add product menu name
2. product content & menu price
3. select product image
click on “publish” button
4. Select product featured(click on star mark)

Follow our theme documentation, Here is our complete theme documentation: https://luzuk.com/demo/lz-restaurant/documentation/

if you need any more help, please message us.

Thank You.