I made my own original cover art image since it is an awkward size for photos. If anyone wants to use it the link is
Also a couple tips: you can use larger resolution if you double or triple the pixel size as long as it is the right dimensions. Make sure you are using a direct link (try a different free image hosting site if yours isn't working). make sure you upload it as a .jpg. Try all those things if you are pasting a link and your cover photo isn't showing up! I had a couple issues and it is complicated because there is no error message - you just have to trouble shoot it yourself.