McDeProductions teaches you how to throw a curveball in softball or baseball. You want to put your thumb on the bottom of the ball and the rest of the fingers a bit apart. You will just roll the ball off the palm of your hand when you throw it, which will give the spinning motion. You have to also keep an eye on the bat and where you want the ball to end up. Use as much or as little power as you think is necessary for the ball to curve the right way. If you don't succeed the first time, keep practicing.