Click and Drag RTS Mouse selecting script help.

Alright. Hey everybody reading this, I'm working on my first RTS project, and I'm having trouble with a piece of code that is pretty complex to me. I'm using raycasts to select objects with the click of a mouse. Not so bad at first, and the typical selecting is no biggie. And by that I mean I can get the console to acknowledge the unit I clicked on. Baby steps.

However, I'm trying to pull of that thing where you click one spot, then move the mouse a bit, and release the mouse button, and the distance between the two clicks becomes a radius in which every unit inside becomes selected. I read a post on the forums and got the Idea of using a Physics.CapsuleCastAll. I'm pretty confused on how I should order everything to get it to work the way I want it to.

If anyone would be so kind as to point all my stupid mistakes, give advice on a better way to set it up, and/or maybe give me a hit on where I can go next to actually get a unit to stay selected until I hit a key or select another unit.

Any help with this would be vastly appreciated, by me and future RTS game makers with the same ambitions.

Here's the script. You'll see some things are empty cuz, Im not done of course.

 #pragma strict
 
 static var radius = startClick.magnitude - endClick.magnitude;
 static var hit : RaycastHit;
 static var endClick : = hit.point;
 static var startClick = hitInfo.point;
 
 function Update () 
 {
  if(Input.GetMouseButtonDown(0))
  {
  var twoSecondsLater = Time.time + 2;
  
  if(Time.time < twoSecondsLater)
  {
 
  
  
  }
  }
 
  if(Input.GetMouseButtonUp(0))
  {
  public var hitInfo : RaycastHit;
  
  if(Input.mousePosition)
  {
  var ray = transform.position;
  
  if(Physics.CapsuleCastAll(ray,Vector3(ray.x, ray.y + 10, ray.z), radius, transform.forward, hitInfo, Mathf.Infinity))
  {
  Selected ();
  }
  }
  } 
 }
 
 
 
 function DefaultSelect ()
 {
  var ray : Ray = camera.ScreenPointToRay(Input.mousePosition);
  
  if(Physics.Raycast(ray, hit, Mathf.Infinity))
  {
  Selected();
  }
  else 
  {
  print ("Did not Hit");
  }
 }
 
 function Selected ()
 {
  var selectedUnit = hit.transform;
  
  Debug.DrawRay (transform.position, transform.TransformDirection (Vector3.forward) * hit.distance, Color.yellow);
  print ("Did Hit");
  
  Debug.Log(hit.collider.gameObject.name + " Selected");
 }