This is not exactly the right thread for this, this would go in feedback requests. Also, if you want feedback, it would be best for you to include a link.
As for covers, I had a similar issue starting out. I was directed to
Canva as a good resource. It's a poster design site, but if you customize your dimensions you can set it to the dimension limits for cover arts. After this, it's just a matter of placing in your picture for a background, and then you can use the site's tools to overlay some text.