At the photos tab you can add multiple photos to 1 product. The photos must be in .JPG, .JPEG, .PNG or .GIF format. Those are file formats that are supported. When you click on the gray box 'Add photo', you can choose a photo from your own computer that will be added directly to the product. The file name of the photo is taken and stored in Gnap. It can be useful to name this file name even more 'descriptive' via the blue icon by adding all kinds of relevant words about the photo you have added. This improves the findability of this photo at Google!
When you click on a photo in Gnap, wait a while, and then drag, you can change the sorting of the photos. This way you can determine later which photo should be in the first position. Deleting a photo is very easy, by moving the mouse over the photo and then clicking on the red icon. When you confirm to the question 'Are you sure you want to delete this photo?' the photo will be deleted.