How to create a menu by pressing a key

Hi everyone.

I'm using this JS right now to freeze the gameplay by pressing the 'b' key;

     private var showingCursor = false;
 
 function Start(){
 
 Screen.showCursor = false;
 
 }
 
 function Update(){
 
     //check if pause button (escape key) is pressed
     if(Input.GetKeyDown("b")){
 
         //check if game is already paused       
         if(showingCursor == true){
         Screen.showCursor = false;
         showingCursor = false;
         Time.timeScale = 1;
         AudioListener.volume = 1;
         }
 
         //else if game isn't paused, then pause it
         else if(showingCursor == false){
         Screen.showCursor = true;
         showingCursor = true;
         Time.timeScale = 0;
         AudioListener.volume = 0;
         }
     }
 }
 

But now, when i press 'b', a menu should be created with buttons. How to do that?

I thought it should maybe something like this;

 var menu = false;
     private var showingCursor = false;
 
 function Start(){
 
 Screen.showCursor = false;
 
 }
 
 function OnGUI () 
  {
     GUI.skin = mySkin;
     
     GUI.Box (Rect (10,10,400,1000), "Main Menu");
     
     if (GUI.Button (Rect (85,50,250,30), "Resume game")) {
         menu = false;
     }
 
     if (GUI.Button (Rect (85,50,250,30), "Go to menu")) {
         Application.LoadLevel(0);
     }
 
 }
 
 function Update(){
 
     //check if pause button (escape key) is pressed
     if(Input.GetKeyDown("b")){
 
         //check if game is already paused       
         if(showingCursor == true){
         Screen.showCursor = false;
         showingCursor = false;
         Time.timeScale = 1;
         AudioListener.volume = 1;
         menu = false;
         }
 
         //else if game isn't paused, then pause it
         else if(showingCursor == false){
         Screen.showCursor = true;
         showingCursor = true;
         Time.timeScale = 0;
         AudioListener.volume = 0;
         menu = true;
         }
     }
 }

But i was wrong. Someone can help me?