Flip the two pieces of carpet that you plan to piece together over and mark arrows on the back of each piece of carpet with chalk along the edges to be joined, showing the way the carpet fibers lean. This will allow two pieces to be joined together and look like one seamless whole. If they are positioned with opposite-leaning fibers, the two carpet pieces may appear to be a different color, even if they are the same exact style.
Place one of the pieces of carpet over the other, faces still down, overlapping it by approximately 3 inches on the back and making sure that their arrows are pointing in the same direction. Trace along the edge of the top carpet with a piece of chalk so that when you place the two together, they will fit perfectly.
Cut along the chalk line using a slide knife. Remove the trimmed piece and discard it.
Keep the carpet face down and place the two edges together as closely as you can. Place a length of seaming tape along the entire edges where the two meet, connecting the two pieces together.
Heat up the seaming iron by plugging it in.
Place the seaming iron on top of the tape at one end. Move the iron along the tape slowly, holding the two pieces together as firmly as possible to ensure that they fuse together. Check to see that the tape melts evenly along both edges.
Allow the tape to cool until it sets. Place the pieced-together carpet onto the floor where you want it to go. Fluff along the top of the carpet fibers to ensure the seam is not visible from the top.