Glue the Seams Together
Where the carpet edges join, you'll need to create a seam. The seamed edges of both carpet segments must be straight. Check the edges: don't assume that a factory edge is straight. Place a piece of seaming tape under the seam, adhesive side up. Heat the seaming iron to the temperature recommended by the tape manufacturer, and rest it directly on the tape for 15 to 30 seconds. Then slowly slide the iron along the tape, and press the seam into the melted glue behind the iron. After the pieces are joined, place heavy objects on the seam to hold it in place as the glue dries. Seams should run parallel to the room's main light source. And make sure the pile of both pieces leans in the same direction.