How to move a GameObject to the mouse position?

I have this so far:

#pragma strict

var cardmove : GameObject;

function Start () {
cardmove.gameObject.transform = KeyCode.Mouse0;
}

function Update () {

}

I am trying to move the cardmove Gameobject that i assign, but when I try to add the Keycode.Mouse0 to my code I get a read only error? How can I fix the read only error and get my script to work?
Can someone help me with this thanks!

you cant set a enumeration value (KeyCode.Mouse0) effectively an int to a Transform(a much more complex struct then anyone gives it credit)

if you want the Vector2 mousePosition Reletive the screen you would use Input.mousePosition though you will need to do work of this to get anything of real value in 3d space.

if you want to know like where the mouse interacts with respect to an object then you would use screen point to ray with respect to the mousePosition