for this tutorial, you'll need pics art and phonto.
first, go into pics art and open up your background
then click add photo and add your png
after that, click apply and click add photo again.
add this template;
click lighten and place it where you want it to be.
after you do that and save it to your camera roll, you'll need to open up phonto.
put the covers name and it should look something like this;