Lay the longer right hand piece, right side down, on top of the shorter left hand piece. Place one or two pins toward the edges if needed. Sew from the top left corner to the bottom right:
Once the pieces are sewn together, you can flip them together into one continuous piece. At this point, it will be very obvious if you sewed in the wrong direction!! You should have a smooth piece that will exactly fit the remaining edge of your quilt. Trim the seam allowance, and finish attaching the binding.Once the binding is attached to the front, I hand-stitch it to the back. If I were to attach the whole thing by machine, I would first attach it to the BACK of my quilt, then bring it to the front in order to cover the first seam. You can use a decorative stitch or a straight seam with matching/invisible thread for this option.
Binding is one of the tedious steps - but it has to be done in order to have a finished quilt! Quilt show judges pay particular attention to this - they also want to see the mitered corners sewn down on the front as well as the back. And some longarmers will attach the binding to the front of the quilt for you, which saves some time if you can afford the extra cost.