Sorry if this doesn't belong in here - please move if necessary. All you'll need to start on this is a blank image of book cover proportions. This will serve as your background and can be any colour you please. Then go here: https://pixlr.com/ - click the two 'down' arrows and launch the Pixlr Express app. Then it's just a case of playing around. You can add layers, borders, text, and all manner of effects. My last three designs in the cover thread were created using this. Thought it might useful for the e-bookers among you.
It looks like a decent enough photo editor, but it does seem to lack the versatility of programs like Photoshop or Corel. It does have a pretty simple interface, which is good for those not trained in graphics software, and if you're making a pretty simple cover for something "real-world", it could work well. For a horror, fantasy or thriller cover, though, it would be pretty limited.
You're both referring to the other program on that site. I'm talking about the Pixlr Express app, not Pixlr Editor. Pixlr Express is not photo editing software in the same way Photoshop or Pixlr Editor is, it's more a design tool.