Here's the front. It's really reversible, but I like this side best.
I folded the flap fabric and stitched the raw edges into the outer edge. The binder slips right in.
Here's the back of the binder.
I went around the outside edge with two rounds of satin stitch. The first time was the middle setting on my machine and the second time was the widest setting. It turned out slightly wonky which feels just right.