How can I get a GameObject's transform in game and set that to a variable?

I am trying to make a simple game where a cube follows you and you kill it. I want to instantiate the cubes, but my problem is setting the transform that the cube goes for After instantiating the enemy. When I don't instantiate and I just click play, it works (because the transform I use here is the GameObject of the first person controller, not the PREFAB). So my big question is, how can I get the transform of my first person controller and set that to the enemy's target? here's my enemy script:

 #pragma strict
 
 var target : Transform;
 var moveSpeed = 3; 
 var rotationSpeed = 3; 
 var myTransform : Transform; 
 
 function Awake(){
     myTransform = transform; 
 }
  
 function Start(){
      target = GameObject.FindWithTag("First Person Controller").transform; 
      Debug.Log (target);
      
 }
  
 function Update () {
     myTransform.rotation = Quaternion.Slerp(myTransform.rotation,
  
     Quaternion.LookRotation(target.position - myTransform.position), rotationSpeed*Time.deltaTime);
  
     myTransform.position += myTransform.forward * moveSpeed * Time.deltaTime;
 }

Thanks for anyone who can help answer my question. If you need any more information I can provide it. PS I'm not good with Java OR C# but I prefer C#. I didn't do this code above, but everything else was all mine. Thanks for help.