Buying Ammo HELP

hey i need help with a script i am trying to make what it does is when i walk up to a gun on a wall a message will pop up saying "250 points click r to reload" and it will minus that many points and refill the ammo a 300 i have 4 scripts two are for the points, ones for the message that script takes you to another one that is going to be the one so when i click r it would make my ammo go to 300 here are them

Here is the first one that is attached to the zombie):

using UnityEngine; using System.Collections;

public class Zombie : MonoBehaviour {

 public int points = 1; 
 
 // You can edit this in the inspector
 
 void OnDestroy()
     
 {
     PointCounter.points += points;
     
 }
 
 

}

The other point counter attached to the player:

using UnityEngine; using System.Collections;

public class PointCounter : MonoBehaviour { public GUISkin guiSkin = null; public static int points = 0;

 void OnGUI()
 {        
     GUI.skin = guiSkin;
     GUI.Label(new Rect(0.0f, 40.0f, 200.0f, 60.0f), points.ToString());
     GUI.skin = null;
     
 }
 
 // Update is called once per frame
 void Update () {
     
     if(PointCounter.points > 29)
         Application.LoadLevel(2);
     
 }
 
 // Use this for initialization
 void Start () {
     PointCounter.points = 0;
     
 }

}

The first script for the ammo buying:

var target : Transform;

function Update () {

var other = gameObject.GetComponent("Gun");

if ( Vector3.Distance(target.position, transform.position ) < 4) {

other.enabled = true;

}

if ( Vector3.Distance(target.position, transform.position ) > 4) {

other.enabled = false;

}

}

the last part of the ammo buying:

var bulletGUI : GUIText;

function OnGUI () {

GUI.Box(Rect(Screen.width /2 - 100,Screen.height /2 - 100,250,200),"250 POINTS CLICK R TO RELOAD");

}

if(Input.GetKeyDown( KeyCode.R ))

i dont know what to do after the if statement

plz help you can reply to this or email me a skully3100@gmail.com