WallpaperEVO give you a platform to make money from your wallpapers simply by adding your AdSense code bellow your wallpaper.
This is allowed by AdSense terms:
You may place your ad code along with the other publisher’s ad code on the same page.
You can find more info here “Ads on the same page or site as another publisher“.
All you need to do is just make 3 AdSense add zones (468×60 Banner for Tablets, 300×250 Medium Rectangle for Smartphones and 728×90 Leaderboard for PC) and add all 3 zones to “Short description about the wallpaper” in “Submit Wallpaper” form like in the image bellow:
Please use the following colors for your ads:
If you don’t know how to do that please check this guide: How to Make Money from your Wallpapers