rotate object when button is pushed

Example: say your playing an RPG and you have the camera set to 3rd person and you want a to rotate him to the left and d to rotate him to the right, how would one do this? i took a look at the ThirdPersonController script from the Lerpz tutorial but this is to big and confusion to be made of proper use. If someone could help it would be appreciated

Use transform.Rotate:

var rotateSpeed = 20.0;

function Update () {
    transform.Rotate(Vector3.up, Input.GetAxis("Horizontal") * rotateSpeed * Time.deltaTime);

where A and D are set up for the Horizontal axis (should be by default).