Lay the carpet runner on the ground. Run your hand over the pile of the carpet. When installed, the pile should run toward the bottom of the stairs. Place the right end of the runner at the top of the stairs.
Cut the tackless strip approximately 1 1/2 inches smaller than the runner. Center in the stairs and attach one at both the bottom of the tread of the stair and the bottom of the riser. The tacks in the strip should face toward the riser.
Cut and attach a carpet pad on each step, each piece running slightly over the nose of the stair.
Fold the beginning, or fringe, of the stair runner slightly under and staple in place under the nose of the first stair.
Position the runner, checking to see if it is directly in the middle, and use the blunt chisel to hammer the runner into place until it catches on the tackless strip. Repeat with each stair.
At the bottom, pull the runner straight down to the floor. Add approximately 4 inches to the bottom of the stair runner.
Cut the back of the runner with a utility knife to trim off any excess.
Tuck the extra 4 inches under the runner. This will help to hide the seam and keep it from fraying.
Use carpet tacks to tack the bottom of the runner to the stairs.