Unroll the carpeting in the room where you want to install it. Try to lay it so the excess around the edges is evenly distributed on each wall.
Start at the lower-left corner of the room by digging the teeth of the knee kicker into the carpet a few inches away from the wall. The flat, vertical pushing side of the kicker covered with rubber should be facing you. Kick the knee kicker with your knee so the carpet gets stretched towards to the corner. Press the carpeting into the tacks beneath it to keep it in place.
Arrange the carpet stretcher so the teeth are facing the lower-right corner. You need to stretch the carpeting horizontally from the lower left to the lower right. Press the carpeting into the tacks in the lower- right corner and all along the lower wall until reaching the lower left. Use a hammer to make sure the carpeting is firmly attached to the tacks.
Stretch the carpeting from the lower-right corner to the upper-right corner by placing the teeth facing the upper corner. Hook the upper right corner with the knee kicker the same way you did with the lower-left corner. Press the carpeting in place as you hook to keep it in the right shape.
Press the carpeting along the right wall, between the upper- and lower-right corners, into the tacks using the hammer again for a secure connection. Place the carpet stretcher in the upper-right corner, with the teeth facing the upper-left corner and stretch the carpeting in that direction.
Hook the upper-left corner and secure it to the tacks like you did in the other corners. Press the carpeting along the upper wall, between the upper corners, into the tack strips below.
Move the stretcher to the middle of the room, so it is horizontal with the teeth facing to the left wall and stretch. The left wall is the only side not secured to the tacks.
Hook the loose carpeting along the left wall with the knee kicker, securing it to the tacks with the hammer.
Trim the carpeting around the perimeter of the room with a carpet trimmer.
Push the edges of the carpeting down between the wall and the tack strips with the point of a screwdriver. Push the carpeting edges under any doorways in the room with the screwdriver, as well.