Installing carpet onto tack strips requires a power stretcher, which is a tool you can rent at most rental outlets. The head of the stretcher hooks into the pile, and it has a series of extension rods that allow the foot to anchor against the baseboard at the opposite side or end of the room. The tool isn't complicated, but it's easier to operate when you understand its anatomy and the sequence you need to follow when stretching a carpet. You usually use it in conjunction with a knee kicker, which is a smaller stretcher used for corners.
Begin stretching a carpet by anchoring one end onto the tack strips, which are the wooden strips full of protruding nails that should be fastened to the subfloor around the perimeter of the room. Pull the edge of the carpet onto the strips and secure it by running a carpet tool or a stiff putty knife between the top of the carpet and the underside of the baseboard.
Position the head of the power stretcher on the carpet about 6 inches from the opposite wall. Turn the knob on the head to adjust the depth of the pins on the underside. They should be long enough to sink into the carpet backing without penetrating it.
Assemble the extension tube in sections until it is almost long enough to reach the starting wall. Connect the tail block and transfer tube section and fine-tune the length of the extension tube by unlocking the auto lock on the transfer tube and pulling out enough tube to anchor the tail block against the baseboard.
Stretch the carpet by pressing down on the lever connected to the head. If you need to lock the stretcher, push the lever laterally toward the head. To release the locked handle, press on it. Don't try to lift it, or you may damage it.
Cut the stretched section of carpet with a carpet knife and then anchor it onto the tack strips with a carpet tool or putty knife. When it's secure, release the tension on the stretcher and move the head about 18 inches toward the side wall. Depending on the room dimensions, you can keep the tail block anchored to the same section of baseboard and change the angle of the stretcher, or move the block laterally to maintain the same angle. Stretch the carpet again and anchor another section to the tack strips.
Anchor one side of the carpet to the tack strips with a knee kicker after you've stretched the length. Power-stretch the other side, and then use the knee kicker to anchor outside corners around posts, doorways and cabinets.