Decide how high up on the wall you want your beadboard to reach, and place your carpenters level against the wall at that height. Assure that the bubble is centered on the level, and use the pencil to make a line around the entire room. Take a step back and make sure that the line is at the height desired.
Cut the beadboard at the height equal to the guide line on the wall with the circular saw and apply carpenters adhesive to the back side. Start in a corner of the room and apply the beadboard on the wall while making sure that it is aligned with the guide line. Place beadboard sheets side by side along the entire wall until the beadboard reaches around the entire room.
Cut chair railing to the length of the wall with the miter saw, and use the nail gun to attach it to the wall directly above the beadboard. Use as few pieces of chair railing as possible. This portion looks best when it consists of one piece across the entire length of the wall.