Need Help on showing GUI Textures on click

Greetings! I trying to make a script where a player collects objects and needs a GUItexture to appear which is supposed to be a check appear on my list;and some errors appear.Sorry I am pretty new to unity and have little programming knowledge, I am really clueless what to add. Thanks for the help.

here are the errors:

• Assets/Script/CollectPapers.js(35,74): BCE0044: expecting (, found 'OnMouseButtonDown'.

• Assets/Script/CollectPapers.js(35,93): BCE0043: Unexpected token: Col.

• Assets/Script/CollectPapers.js(35,108): UCE0001: ';' expected. Insert a semicolon at the end.

here is my script:

 #pragma strict
 @script RequireComponent ( AudioSource )
 var papers : int = 0 ;
 var papersToWin = 5;
 var distanceToPaper : float = 2.5;
 
 public var paperPickup : AudioClip;
 
 
 function Start ()
 {
 
     Screen.lockCursor = true;
 }
 function Update ()
 {
     if(Input.GetMouseButtonDown (0) || Input.GetKeyDown (KeyCode.E))
     {
         var ray = Camera.main.ScreenPointToRay(Vector3(Screen.width * 0.5,Screen.height * 0.5, 0.0));
         var hit : RaycastHit;
 
         if(Physics.Raycast(ray, hit, distanceToPaper))
         {
             if(hit.collider.gameObject.name == "Paper")
                     
             {        
                 papers += 1;
                 audio.PlayClipAtPoint(paperPickup, transform.position);
                 Destroy(hit.collider.gameObject);    
                     
                     {
                         var guiShow : boolean = false;
                         var riddle : Texture;
                             {                                
                                 {
                                     if(hit.collider.gameObject.name == "Paper")
                                         {
                                             guiShow = true;
                                         }
                                 }
                             
                             }                
                     
                     }
             }
             
         }
     }
 }
     
  function OnGUI()  {      
  if ( papers < papersToWin )      
      
      {          
          GUI.Box( Rect( (Screen.width * 0.5) - 60, 10, 120, 25 ), "" + papers.ToString() + " Object/s" );      
      }      
  else      
          {          
              GUI.Box( Rect( (Screen.width/2)-100, 10, 200, 35 ), "All Objects Collected!" );          
                  Application.LoadLevel( "Real Menu" );      
          }  
  }
 

The checks are supposed to appear here