Measure the staircase with the measuring tape. Add three inches per step to make sure you have enough. This will let you know how much carpet material you need for the project.
Attach tack strips to the thread and riser of each stair, right next to the wall. Hammer them into each stair with the nails.
Lay the underpad on the horizontal part of each step between the tack strips. Use glue to adhere it to the staircase.
Starting from the bottom of the staircase, place the carpet on the horizontal and vertical parts of the stair. Place the carpet over the tack strips so that some of it catches on them and press it into place with the wedging tool.
Secure the carpet to the stairs starting from the bottom stair and working your way upward. Use the knee kicker to press all of the carpet on both sides into the tack strips. Fold some of the excess carpet into corners on each horizontal section and wedge it into the stair intersection with the wedging tool and a hammer.