Make a event happen every 4 seconds?

How do i make something happen every 5 seconds? I have this script that spawns a object at start. But i want it to spawn a object every 5 second.
How do i implement it?

#pragma strict

var rndNum:int;
var less = 5;
var asteroid : Transform;
var myposition : GameObject;
var spawn = true;

function Start() {


Instantiate(asteroid, myposition.transform.position, myposition.transform.rotation);




}

You can use InvokeRepeating to make a function occur at regular intervals.

Or you could use a for next or while loop and yield WaitForSeconds:

 function Start() {
       while(true) {
            Instantiate...
            yield WaitForSeconds(4);
       }
 }