If you had a gallery wall hanging in one of your rooms, you probably noticed all of the small nail holes left in your wall when taking it down. Patching these holes is easy. All you need is a spackling paste, a putty knife, and sandpaper. First, prepare the holes by using your putty knife to clean out any excess debris. Next, load your putty knife with a generous amount of spackle and force it into the hole in the wall. Don't worry about getting spackle on your wall. Focus on filling the hole. Line up the flat edge of your putty knife with the wall, just above the filled-in area, and drag it across the hole once more. Once it's dry, use the sandpaper to lightly sand the area to leave a smooth, flat wall.