CS1519 C# error `void'?

Help me where did I go wrong?

using UnityEngine; using System.Collections;

public class Parallaxing : MonoBehaviour { public Transform [] backgrounds; // Array (list) of all the back and foregrounds to be parallaxed private float [] parallaxScales; // The proportion of the camera's movement to move the backgrounds by public float [] smoothing = 1f; // How smooth the parallax is going to be. Make sure to set this above zero

 private Transform cam;                     // Refrence to the main camera's transform
 private Vector3 PreviousCamPos             // the position of the camera in its previous frame
  
 // Is called before Start (). Great for references
  void Awake () {
             // set up camera the reference
             cam = Camera.main.transform;
 
     }

 // Use this for initialization
 void Start () {
     // The previous frame had the current frame's camera precision 
     PreviousCamPos = cam.position;

     // assigning corresponding parralax scales
     parallaxScales = new float[backgrounds.Length]; 
     for (int i = 0; i < backgrounds.Length; i++) {
         parallaxScales[i] = backgrounds[i].position.z*-1;
     }
 }
 
 // Update is called once per frame
 void Update () {

     // for each background
     for (int i = 0; i < backgrounds.Length; i++) {
                     // The parallax is the opposite of the camera movement because the previous frame multiplied by the scaale
                     float parallax = (PreviousCamPos.x - Cam.position.x) * parallaxScales [i]; 
                     // set a target x position which is the current position + the parallax
                     float backgroundTargetPosX = background [i].position.x = parallax;
 
                     // create a target position which is the background current position with it's target x position 
                     Vector3 backgroundTargetPos = new Vector3 (backgroundTargetPosX, backgrounds [i].position.y, backgrounds [i].position.z);

                     // fade between current position and the target position using what is called lerp
                     backgrounds [i].position = Vector3.Lerp (backgrounds [i].position, backgroundTargetPos, smoothing * Time.deltaTime); 
             }

     // set the previous Pos to the camera's Pos at the end of the frame
         PreviousCamPos = cam.position;
     }

 }