How to add SFX to thia script

how to add SFX to this script pls help i have no idea #pragma strict var fireballbullet : Transform;

 function Start () {
 
 }
 
 function Update () 
 {
     if (Input.GetKey("space"))
     {
         var bulletfire = Instantiate (fireballbullet,gameObject.Find("Bullet Spawn Point").transform.position,Quaternion.identity);
         bulletfire.rigidbody.AddForce(transform.forward * 50000) ;
     }
 }