Couching is simply sewing a heavy thread in place with a finer thread. It works beautifully by machine as well. I use a zigzag stitch to secure the heavy thread in place. And, if you have a cording foot— the foot guides the thread as you sew.
How to build a pattern cuffs dress
*Concise Solid Color V-Neck Sleeve Chiffon Blouse For WomenBlouses… (Maybe in a brighter color)