The covers above are not mine, but it is what we are going for. I can approximate all the covers using PowerPoint. You will get a nice cover. Sometimes symbols are more important than beauty, as you can see, third cover to the right is reallly ugly, but sells really well. SYMBOLS are the key.
I will provide a sketch draft of a cover that sells in thumbnail size (not for publication)
Good covers are not pretty, they speak in symbolic language to the left side of the buyer's brain. This is why ugly covers sell and pretty covers may not. It is all about that message in symbolic language.
Send the wrong message, and they buyer will not click.
Send the right message and the buyer will press buy or get a sample.
For extra, I will create the cover in PowerPoint 2013, give you the editable file and renter the images for Kindle and Create Space.