HI! One of the best programs for making wallpapers is Adobe Photoshop...though it is rather expensive. I do believe there are a few free or inexpensive ones to be found if you look online. Once you find the program, just look around for screencaps and promo pictures and start arting. Just remember to be creative and use your own ideas, artists get pretty cranky if you start chopping up their work and calling it your own. Have fun and Good luck.