Rotation - rotate ship to face mouse cursor

I'm making a top down space shooter. I'm trying to make it so the ship will rotate to face the mouse cursor. The problem here is I've made virtually no progress. I've got something that will rotate but not as I want it to.

My Z axis is what will be perceived as the vertical axis. This is my code (javascript) for it:

var rotationSpeed = 100.0;

function Update () {

var rotate =  Input.GetAxis("Mouse Y")  * Time.deltaTime * rotationSpeed;

transform.Rotate (0, 0, rotate);
}

My ship is made up of three parts until I get an actual model for it. The Ship body which is the parent of the other parts and the camera, the front (basically nose), and the wings. The camera is positioned above the ship, looking directly down at it.

I know it's not correct for what I need it to do by it's the furthest I've got with it so far. I'm just looking for something that will appear to rotate the ship left and right.

I'm also looking to possibly rotate the ship to face the opposite direction of the mouse cursor as it may make for better controls (clicking the mouse moves the ship).

Any help towards this would be appreciated. I'm fairly new to Unity, I've gone through a fair number of tutorials and have been stuck on this for hours.

Hi GTS,

This has been asked before, have a look at this post..

http://answers.unity3d.com/questions/37536/rotate-towards-mouse