Lay your carpet pieces, overlapping the two sections you are joining. Make sure the nap on the carpet is facing the same direction on both pieces.
Cut through both pieces of carpet at the center point of the overlap with a carpet or utility knife and a straight edge.
Place a piece of seaming tape on the floor, centered under the seam and adhesive side up.
Heat the seaming iron to the temperature recommended for the type of seaming tape you are using.
Starting at the end of the seam, lift both pieces of carpet and place the heated seaming iron on the tape. When the tape starts to melt, usually after about 15 to 30 seconds, slide the seaming iron down the tape, pressing the carpet pieces down as you go.
Use a carpet roller or rolling pin to firmly press the carpet pieces onto the tape. Place heavy items as weights along your seam to keep the carpet in place as the tape sets.