For Three Prong Cords
the Center cord wire goes on the center terminal,
the left on the left ,
and the right on the right.
Note: There should be a ground strap or wire that runs from the center terminal to the dryer case. For Four Prong Cords
the White cord wire goes in the center,
the Red on the Right,
the Black on the Left.
The green cord wire goes to the case or the external ground screw.
Note: Be sure to disconnect the ground wire or strap that runs from the center terminal to the case. In this Photo (A Whirlpool Dryer) I have ran the wire that runs from the center terminal, the Light Green wire, back to itself rather than cutting it off, just incase I need to put a 3 prong cord back on it some day. The whole purpose of this 3 prong / 4 prong thing is it separates the neutral from the ground.