Measure the area to be carpeted.
Use a utility knife to cut your attached pad carpeting to 1 inch larger on each side than the measurement you took. So, for example, if you were going to carpet an area 78 inches across, you'd cut the carpet for that area to be 80 inches across; one inch extra on each side.
Lay the carpet out on the surface to be carpeted.
Kneel near the edge of your carpeting and pull the edge of the carpet back.
Apply an even strip of carpet tape, which is basically a strong two-sided adhesive, along the floor's edge where the carpet will lay.
Remove the paper backing from the carpet tape, revealing the upward-facing adhesive.
Drop the carpet back into place over the carpet tape and smooth it into place along the entire length of the tape.
Trim any extra carpeting away with a utility knife.
Repeat this process with all other edges of the carpeting. Peel the carpet back, apply carpeting tape, replace the carpet and press it into place, then trim away any extra carpeting.