Measure to get the amount you need in carpet. Measure the tread horizontally to get the width, the tread is the horizontal board on the stair. Add the height to this and then add the length under the nose to get the total. Add an additional 3 inches per stair for the padding that will be underneath the carpet.
Measure the length at the stair crotch and cut the tack strip to the appropriate length with your saw.
Put on your safety glasses.
Nail down the tack strip with your hammer at the stair crotch.
Measure and cut your padding to fit on the tread and roll over the nose of the stair.
Staple the padding down onto the tread.
Start at the bottom of the staircase. Staple the carpet to the bottom of the first riser.
Bring the carpet up onto the first step from the bottom of the staircase and place the carpet over the padding. Tighten the carpet by tucking it into the crotch with the knee kicker. Wear your knee pads and place the knee kicker, teeth side down, on the carpet and then kick the padded part of the knee kicker with your knee.
Stretch the carpet in the center of the tread and hook it onto the tack strip. To do this you will need to use your knee kicker by placing the teeth side down on the carpet and then kick the padded part of the knee kicker with your knee.
Inspect to make sure the carpet is firmly attached to the tack strip by sliding the kicker in a back and forth motion to tighten the carpet onto the pins on the tack strip.
Trim the excess carpet on each side of the tread with your utility knife. Hammer the sides into the space between the stair and wall with your stair tool.
Look to make sure the carpet is smooth. Staple the spots that need extra security to keep it tight.
Continue with installation on each step, stapling the carpet on the risers until finished.