From the dashboard, click FOOD in the left menu panel. From here, you can select any item to show a right menu panel. There, you can edit the Name, SKU, Price, Description, and Category of any food item. You can also provide a picture of the food by clicking IMAGES next to details.
This is the menu from which you can edit your items. As seen, the Arugula Salad is selected, with options to adjust the variables in the right menu panel.