In this tutorial, we learn how to do the mattress stitch. First, lay the pieces flat and thread yarn tail onto the needle. Next, you will anchor the yarn to the bottom edge of the opposite piece. Then, go back through the side and find the tunnel of horizontal bars, one stitch in from the edge. Continue to do this around the stitches to combine them together. Keep alternating sides and just do one bar at a time to get the best results. You can do two bars at a time if you are comfortable with it. After this, you will be finished with your mattress stitch!