Tank Turret move on XAxis by Mouse XAxis

i am on day 4 of using Unity/Blender, i copy and paste a lot from tutorial on youtube

my game so far http://www.filehosting.org/file/details/417047/50zVAEimUmy70kkx/Game-Poulpc.rar

i have try using the script form this video http://youtu.be/ypSkxGRY218?t=6m17s but i have more the one camera

only one the came close was this one

var rotationSpeed = 100.0;

 function Update () {
 var zdir = Input.GetAxis("Mouse X");
 transform.Rotate(zdir * rotationSpeed * Time.deltaTime, 0, 0);
 }
 

but that moves the turret up and down, not left and right

looked a loot on this page to, but most use keys to move it or MouseDrag or ray

only thing i am looking for is a script that i can put on my turret that makes it move, right and left when i move my mouse right and left

or and noob tutorial