Cover for History of the Trap

This is a photo that I was trying to use as a cover of my History of the Trap story on Smashwords.  I tried to format it through a photo-shop type program called Gimp, and that proved to be an utter failure.  I would show you my efforts, but I couldn't even get them to upload here.  If anybody has any suggestions as to good programs to generate ebook covers, please let me know.  I would greatly appreciate it!

And yes, this is my alma mater, Bridgeport High School, the true setting for History of the Trap.