How can I add the game object from above (Roed Knap, Hand etc.) into the script given below (at the picture)?

This is an example project. I can't figure out to reference GameObject's and Colliders into a Script.
What I want to do is very simple.
Make a GameObject with a Collider, and trigger something when collision happens.
So What I have is basically a GameObject Cube that has a Collider sphere added and for this isTrigger is selected. I want this trigger when entering, modify the text. Can you help me with initializing, referencing and other stuffs necessary, see below code. This is the code I work with.
using UnityEngine;
using System.Collections;
public class NewBehaviourScript : MonoBehaviour {
GameObject Cube;
GUIText Text;
Collider collision;
// Use this for initialization
void Start () {
collision = Cube.GetComponent<Collider> ();
Text = GetComponent ("GuiText") as GUIText;
}
// Update is called once per frame
void Update () {
}
void onTriggerEnter(){
Text.text = "Won"
}
}