Once you’ve selected your book size, click on the “Add Cover” button in the upper right hand corner of the screen. From there, you can select a cover photo from your camera roll. Once the photo is chosen and added to your book, you will see two tools in the bottom right hand corner of the image. A cropping tool (image) and a delete tool (image). If you wish to change your cover photo, select the delete tool to remove it and then choose another photo from your camera roll.