Hi, I just watched your Contractor Training DVD. Very informative. Well worth the money. It explained almost everything in a lot of detail. The one thing that the DVD didn't explain very well was how do you attach the green to the sub-surface? In section 15, you discuss applying the infill. And let's suppose there is no fringe being installed. So we skip to section 17, which is "sweeping infil off of the green". But didn't we skip a step? You don't need to nail down the green first? What keeps the green attached to the sub-surface? Just the weight of the infill?