Tutorial time!! This only covers the base; not the text or coloring. If you want a tutorial or any help on those, feel free to ask. Please note that this is just the way I do covers and is of no means official. Feel free to simply use this to get ideas!

App used: IbisPaint X

1. First open IbisPaint X. Start with a blank cover template and place down your render. You can change the placement of it later, it's just better to start off with it so you get a good idea of what to do.

2. Place your 'main' texture behind the render. If it doesn't work as well as you thought it would, use some filters to alter the color, saturation, etc.

3. Use the airbrush pen and spray some parts around the cover, usually where parts of the render end.

4. Place down another texture you think will look good...

5. And clip it to the previous layer! This is a very easy way to blend backgrounds together.

6. I added a shadow behind the character and made her a little smaller. Here's also a (secret) way to make a character 'glow', per say. Duplicate the render, use gaussian blur on it, then set the layer style to lighter color! The more you blur the render the brighter it'll be. Also if it gets too bright in some areas, then simply erase those parts! I did that to the eyes, nose, and mouth.

7. Ended up playing with some more textures and colors. Whoops-

8. Next comes the fun part; pngs! In case you don't know, png's are already rendered pictures, like a balloon or flower. Sorry I'm bad at explaining-
Anyways, just have fun with this part! It may take awhile to place them all the way you want. I didn't add many, only four. But sometimes you don't need a lot of pngs. Just place the ones you feel like will enhance the cover, not take away from it.

And you end up with something like this!! ^^

I'll be ending the tutorial here. I'm not the best at explaining text and all that, so all I can say is have fun and experiment with it! Making graphics is about having fun, so do what you feel like is necessary. Hope this helps anyone, and if you have any questions then please ask!! Love y'all!