Decide if you want to hang the wall border around the middle of the walls at chair-rail level, or at the top of the walls near the ceiling. If hanging mid-wall, use a tape measure and a pencil to make marks along the wall -- all the way around the room -- to mark where to hang the border. Check often with a level to ensure you have a straight line. Take special notice around doors and windows to make sure the border will be at the same height on either side.
Most Disney Baby brand wall borders are self-stick or prepasted for easy installation. If self-stick, peel the backing off the wall border and stick the border to the wall. If prepasted, submerge sections of the wall border -- with the image side down -- in a tray of warm water. Allow the border to soak for a couple of minutes to activate the paste.
Start in one corner of the room and start applying the wall border to the wall, smoothing with a wallpaper brush as you go. Take your time and go slowly. Since this border features a colorful pattern with character images, make sure you cut the next border strip to match the picture where the last border strip ended. For example, if the first piece of border ends with Winnie-the-Pooh's face on it, use a utility knife to cut and start the next section with the same picture, overlapping for a seamless look. Continue around the room using the same steps until all four walls have border.