How to hit an underhand and overhand serve in volleyball, and what are the advantages and disadvantages of both types of serves?

When hitting an underhand ball, you need to make a fist and have the bottom of your wrist facing toward the ceiling. Then, when you want to hit the ball, you need to keep your arm straight and towards the opposing team.

When hitting an overhand ball, you need to make your arm look like a backwards right triangle with your fingers spread apart and have your hand flat. Throw the volleyball up slightly above your head, but in front of your face. lift the opposite arm up straight and hit the volleyball toward with force over the net.

Ibelieve the answer is the second one. plz don't kill me if i got it wrong. > .<