i have 2 assets , i want to make a text appear after a collision between them (and end the game if that is possible) , how can i do that ?

I know this doesn't answer your problems completely, but it might help a bit.

using UnityEngine; using System.Collections;

public class NextLevel : MonoBehaviour {

 void OnTriggerEnter(Collider other)
 {
     if (other.gameObject.tag == "Player")
         Application.LoadLevel(1);
 }
 

}

Use this script with an Event Trigger, and it should take you to another scene. Just make sure you go to build settings to apply the scene you want.