Not sure of anywhere that shows you how to do it, but I was taught by Stan at Aim4Sport one day when it was quiet there after plying him with cups of tea 'n coffee. It's not hard to learn if you can find someone to show you like that and you'll probably find it easier than learning from a "how-to" site or the like... Learning from someone who knows what they're doing is great as they can see where you might not be going right and give you lots of little pointers you might not get otherwise!
