I learned by watching 80 something year old men on YouTube...OVER AND OVER AND OVER. And practicing on scrap leather. The style of "Lacing" or "Stitching" on the three sides is called a double loop lace and along the top is a true whipstitch. A friend of mine who makes leather handbags and accessories by hand jokes that we should start a Women Working With Leather type channel. Her talking about sewing and cutting leather, me how to do decorative stitchingI think a tutorial is needed on whipstitching....because that is seriously cool.

What did you use for the dye?
I custom mixed. It was Fiebing's Navy Blue (only blue dye on hand) mixed with LOOOTS of alcohol to dilute the color (about 1/10 dye and 9/10 alcohol) with a DROP of Fiebing's Kelly Green leather dye. The edges didn't take so I had to concoct a leather paint/puffy paint mixture. I could not tell you my mixture for that because it was alot of trial and error to match the dye (I was using what I had on hand)