Hey, I know a good app that you may be able to use for covers. https://spark.adobe.com/make/photo-collage-maker/
To start, just click "Design your free collage now". You can make photo collages or just put one photo in there. I recommend using the "Poster" format. It fits the book covers the best. They tons of amazing picture, and you can also look pictures up online, drag them to the page where you find your photos, and it when you click "Next", you can begin. :) I'm sure you'll figure out the rest once you get in there. It's super easy. :) Enjoy!
