Before you wash your wall paper, you need to know if your wallpaper is washable. Try washing an area behind a piece of furniture first. If the colour does not run and water does not damage your wall paper that means your wall paper is washable. If your paper is washable, you can use a mild soap or mild dish washing soap. Mix a little mild soap with half a bucket of water. Use a sponge to clean, move the soapy sponge in circular motion on the wallpaper. Immediately rinse with another sponge with fresh water. To dry, pat the wall with a dry, clean cotton cloth and remove all the moisture from the paper. Let it dry completely. Repeat the process it needed.