Images can be added to your covers using the Cover Design Tool.
Accepted file types: jpg, jpeg, png
Click the 'IMAGE' option on the tool bar at the bottom of the page.
Browse for your image and click 'Open' to add it to your cover
Once the image has been added, select it and move it into position.
You can resize the image by grabbing the corners.
You also have the options to crop, mask, rotate, move forward/backward, duplicate and delete using the image tool bar, which appears once you have clicked on your image.