Faux leather look is actually embossed polyester felt, made from recycled plastic water bottles. Easily available in the felt section of your favorite craft shop. The more it's handled, the more "leathery" it looks! So don't worry if the stuff you find in the store looks a little plain at first.
Right sides up, overlap the two "leather" felt pieces by 3/4" and tack in place with glue stick. [This measure is the spine of the notebook plus 1/2".]
Stitch along both felt edges. Use a big stitch width for the look of top-stitching on leather.
Next, center notebook over stitching on wrong side of felts, 1/8" above bottom edge. Draw around notebook.
Align felt scraps at bottom edge of felt, overlapping drawn notebook ends. Pin in place. These are the inside flaps of your book cover. Redraw notebook so outline can be seen on the new pieces.
Stitch just to the right (outside) of drawn line. Stitch the entire notebook outline. [Hint: It's easiest to follow the drawn line with pressure foot center, as you would for regular sewing. So move your needle position a tiny bit to the right and voila! you are stitching outside of the line.]
Check that your notebook fits inside cover. Adjust stitching line if necessary.
Trim close to stitching line.
Congratulations! You are done:)