I've got a HUGE library of great-looking photos that I've been turning into iPhone wallpaper images. Since I'm doing it for me, I figured I'd post them for YOU in case you wanted to use them, too.
The top one is for iPhone 4S and the bottom is for iPhone 5 and 5S. You should be able to save it to your phone's camera roll, and from there, set it as wallpaper.
Hot enough for you? Cool off with this image of snow on the Catalina Mountains, behind the city of Tucson.