Player touch item?

You can do this :

 Application.LoadLevel ("TheNameOfYourScene");

but I think you will need more than that to do what you want after this small step.

Have a look at the Input class in the script reference : http://docs.unity3d.com/Documentation/ScriptReference/Input.html

I'm more of a c# guy, so I'm not going to try to write the script but the logic would be somehting like this:

1/ Add a boxcollider to your cube

2/ Write a script with this logic in it and add it to your camera for example.

 var cubeCollider : Collider;

 if(Input.GetButtonDown(0)) // you should change this if you're using multi-touch
 {
     Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition); // also to be changed if on multitouch
     RaycastHit hit;
     if (Physics.Raycast(ray, out hit, 100)) // cast a ray and check if something was hit
     {
        if(hit.collider == cubeCollider) // if something was hit, check if collider is that of the cube
        {
            Application.LoadLevel(1); // Loading scene 1
        }
     }
 }

3/ drag your cube in the cubeCollider variable exposed in the inspector