I love leaving this sort of thing to user innovation, so I have not previously included instructions with the Snackhole. All bikes are different, and the beauty of the Snackhole is that the strap positions can all be tweaked to get just the right fit on pretty much any bike. This diagram gives you a starting place--strap it on, go for a ride, and adjust if you find wobbles.
Another tip: Try placing the abrasive side of the Velcro outward (soft fuzzy side against your bike). With time, especially when riding unpaved surfaces, the abrasive side of the Velcro may wear through the paint or enameled surface.