How do I add sound to this script

I have a script for shooting my gun (you can have if you wish) I need to make it so i can add a audio to this script like a gun shot sound

Script /

var prefabBullet:Transform;
var shootForce:float;

function Update()
{
	if(Input.GetButtonDown("Fire1"))
	{
		var instanceBullet = Instantiate(prefabBullet, transform.position, Quaternion.identity);
		instanceBullet.rigidbody.AddForce(transform.forward * shootForce);
	}
}

Add an audioSource to your gun, drag the sound you want to shootSound in the Inspector and fire the sound using:

var shootSound:AudioClip;

function Update(){
  if (Input.GetButtonDown("Fire1")){
    audio.PlayOneShot(shootSound);
    var instanceBullet = Instantiate(prefabBullet, transform.position, Quaternion.identity);
    instanceBullet.rigidbody.AddForce(transform.forward * shootForce);
  }
}

I edited the script a little just for the sound. I did this:

var shootSound:AudioClip;

function Update(){
if (Input.GetButtonDown(“Fire1”)){
} audio.PlayOneShot(shootSound)};

Now I get a bunch of errors. What did I do wrong?