reloadtime

hello i dont know how i make a reloadtime on this script can u help me

 var projectile : Transform;
 
 var speed = 1;
 
 var barrel : Transform;
 
 var shootSound: AudioClip;
 
 var shots :  int  =  0 ;
 
 var maxShots :  int  =  8 ;
 
 var reloadSound: AudioClip;
 
 function Update () {
 
 if ( Input.GetButtonDown ("Fire1") && shots < maxShots){
 audio.PlayOneShot (shootSound);
 
 clone = Instantiate(projectile, barrel.position, barrel.rotation);
 
 clone.rigidbody.velocity = barrel.TransformDirection( Vector3 (0, 0, speed)); 
 shots ++;
 
 }
 else if (shots >= maxShots && Input.GetKeyDown(KeyCode.R))
     {
 audio.PlayOneShot (reloadSound);    
         shots = 0;
     }
 }