Step One: Cut bias strips wide enough to cover the size of welt cord you are using plus several extra inches for pulling and turning under the edge of your project. Cut enough pieces to trim your project. Sew bias strips together and press seams open.
Step Two: At the sewing machine, place the bias strip face up and turn over the right edge. (To determine how much to turn over, test with a piece of welt cord). Place the welt cord on the folded-over fabric, 1/2" from the right edge. Wrap the fabric over and sew all together using a cording foot on the sewing machine.
Step Three: After the welt is sewn, there is a clean seam with no stitches showing. Apply to the edge of your upholstery project with tack strip and staples or hot melt glue.