To access this page click on edit in a product and then click on "Images." At this example, we´re customizing our ordering app, but if you´re customizing another app could appear more or fewer images.
1.- This is a preview of the picture you selected.
2.- This is the description of the image, indicates where the image is used and specify the scale in pixels that the picture must have before upload.
3.- Click here to upload your image, when clicking on "change" appears a new window to choose a picture from your computer. If the image doesn´t have the proper format (must be .png) and size (indicated in the description), won´t let you upload your image.
4.- Click to save changes to your app, to exit from this page you can click at any of the tabs from the navigation bar at the top of the page.
This video-tutorial that will help you better understand this topic.
Glad we can help!
Have a nice Ordering