Check that the tack strips are firmly in place and the majority of tacks are not broken and are leaning toward the wall. Make any adjustments to the pad necessary before stretching the carpet, and be sure to keep the pad off the tack strips.
Lay the carpet edge over the tack strip in one of the corners of the room furthest from the exit. Make sure there is at least an inch of carpeting over the strip. Position a knee kicker so that it rests on the carpet. Make sure the end with the teeth is down on the carpet a few inches from the wall.
Place a knee against the padded end of the tool and begin kicking at it repeatedly. The intent is to push the carpet ahead and catch it on the tack strip. When the strips catch the carpet backing and the kicking stops, the carpet naturally tries to go back to its prior position but stays in place instead.
Go to the opposite corner of the room and perform the same action. This will help add tension at the corners and allow the carpet to be stretched evenly. When all four main corners are done, go back to the original starting corner and begin stretching along the wall. Position the kicker approximately every foot along the wall and stretch it as evenly as possible.
Move to the opposing wall and tighten it down in the same fashion to keep the carpet even. Do the remaining two walls the same, starting with one, and then doing the opposing. Check the carpet for any lines or visible creases. If necessary, use the kicker again to try to pull the carpet tighter.