where should i pitch the ball for a perfect yoker

plzz tell me where i have to aim

Aim at the legs of the batsman and it should pitch after the crease .

Depending on your natural length of pitching the ball. To bowl the perfect yorker, adjust the release of the ball from your hand so that you pitch it on the crease line. This will either bowl or LBW the batsman or they block it out for no run.