rotate twords mouse

Hi how whould I change my rotation from using W to rotate charcter left and R to rotate my character right to rotate my character on where my mouse is.

A game example would be minecraft movement in which your character rotates on where your mouse is.

Also like most fps

Thanks

Here is my code which is in java

var speed:float=10; 
var rotatespeed:float=50;

function Update() 
{ 
    //Movement 
    if (Input.GetKey("w"))
    {
        transform.Translate(0,0,speed * Time.deltaTime);
    }

    if (Input.GetKey("s"))
    {
        transform.Translate(0,0,- speed * Time.deltaTime);
    }

    if (Input.GetKey("a"))
    {
         transform.Rotate(0,-rotatespeed * Time.deltaTime,0);
    }

    if (Input.GetKey("d"))
    {
        transform.Rotate(0,rotatespeed * Time.deltaTime,0);
    }
}

If you’re actually using this for a character then you should be using a Character Controller and it’s Class functions. Check out http://unity3d.com/support/documentation/ScriptReference/CharacterController.html