skullbusterz teaches you how to throw a curveball in baseball by flicking your wrist. For the grip on the ball put your index and middle fingers on the left side of the ball. The thumb should be on the bottom, on the opposite side. When you throw the ball make sure you flick your wrist, to give it that spinning motion. Also keep the rim of your fingers towards the sky. You want to keep your eyes on your target and use as much or little force you need to throw the ball. It might be difficult at first, but practice makes perfect.