The instructions involve cutting two strips of fabric, 1 1/2" wide for the binding strip and 1 3/4" wide for the flange strip. (Use mitered seams to connect the strips to make the lengths needed for your project.) The binding strips are sewn together right sides together along the long sides.
The strips are then turned wrong sides together and pressed even at the open edge; the flange fabric will show 1/8" at the folded edge.
The binding is sewn to the back of the quilt with the flange fabric up, then folded to the front of the quilt. The binding is machine sewn with matching threads.
Below the binding is being sewn on. You can see the binding back matches the border/backing fabric of the project and the flange is in the contrasting lighter fabric.
The mitered corners will need to be hand sewn.