setting up mouse button

editor is saying the fire button isnt set up.
im following code from a video/book.im very new to unity.

var speed = 3.0;

var crateprefab:Transform;

function Update()
{
if(Input.GetButtonDown(“fire1”))
{
var crate = Instantiate(crateprefab,Transform.position,Quaternion.identity);

crate.Rigidbody.Addforce(Transform.forward *2000);
}

}

The default reference of left mouse-click is

Fire1

You need to capitalise the ‘F’ in “fire1”.

cheers mate
actually finished a different script as i kept getting errors even after capitalizing the “f”.