Fold the bias strip in half and press. I used 3" but I htink that was a bit wide for only a 1/4" seam. You ideally want your strip to be 6x the finished binding width.
Keeping bias strip folded, pin in place on the right side, raw edges together. Here I'm doing both the straight and curved edges at the same time. For the curved edge, I pressed the bias strip to a curve so it would pin nicely.
Press after stitching.
Press seam allowances towards binding.
Wrap bias binding around to the back. Press and pin in place.
On the curved part, I topstitched. On the straight part, I stitched in the ditch. You could also hand slip stitch it on the back.
Here's what the back looks like.
Note: A double bias binding is also called a French binding sometimes.