Stuck with sliding GUI panels

Hi there,

I have 2 GUI panels in my scene. What I'm trying to do is have the first panel move off of screen to the right and then bring in the second one in from the left to the same position as the first. At present I have coded the two Panels, but not sure what action to add to the first button to bring in the second panel and where it should go in the code.

Ideally, I would also like the 2nd panel to move off of screen as well when a button is clicked (like the first panel).

p.s. using iTween

Any help with understanding this would be great. Here's my code so far:

 using UnityEngine;
 using System.Collections;
  
 public class IntroPanels : MonoBehaviour
  
  
 {
  
     //LeftNav GUI skin reference
     public GUISkin IntroPanels1;
     
     //Panel 2 MenuRect2 = The panel 2. Box2 rect = the button
     public bool menu2RectState = false;
     public bool box2RectState = false;
     //Panel
     public Rect menu2Rect = new Rect(-1000,184,600,400); //MENU PANEL
     public Rect initialPositionMenu2 = new Rect(-1000,184,600,400); //MENU PANEL
     public Rect activePositionMenu2 = new Rect(212,184,600,400); //MENU PANEL
     //Button
     public Rect box2Rect = new Rect(235,280,120,50);  //MENU BUTTON
     public Rect initialPositionbox2 = new Rect(235,280,120,30); //MENU BUTTON
     public Rect activePositionbox2 = new Rect(235,280,120,50);//MENU BUTTON
     ////
  
     //Panel 1 Menu1Rect = The panel. Boxrect = the button
     public bool menu1RectState = false;
     public bool boxRectState = false;
     //Panel
     public Rect menu1Rect = new Rect(212,184,600,400); //MENU PANEL
     public Rect initialPositionMenu = new Rect(212,184,600,400); //MENU PANEL
     public Rect activePositionMenu = new Rect(1200,184,600,400); //MENU PANEL
     //Button
     public Rect boxRect = new Rect(235,280,120,50);  //MENU BUTTON
     public Rect initialPosition = new Rect(235,280,120,30); //MENU BUTTON
     public Rect activePosition = new Rect(235,280,120,50);//MENU BUTTON
     ////
     
 
 
     
     //AUDIO
     
      public AudioClip PlanetMenuSound;
     
  void OnGUI()
     {
  
        //GUISkin for Group
        GUI.skin = IntroPanels1;
         
         
         ////////////////Panel2
         
         GUI.BeginGroup(menu2Rect, "","Panel2");
 
        if(GUI.Button(box2Rect,"","Panel2Button")) 
             
        {    
             
         audio.PlayOneShot(PlanetMenuSound);
  
          if(menu2RectState)
          {
          iTween.ValueTo(gameObject,iTween.Hash("from",menu2Rect,"to",initialPositionMenu,"onupdate","MoveMenu2","easetype","easeinoutback")); 
          }
          else
          {
          iTween.ValueTo(gameObject,iTween.Hash("from",menu2Rect,"to",activePositionMenu,"onupdate","MoveMenu2","easetype","easeinoutback"));
          }
          menu2RectState = !menu2RectState;
             
             
          if(boxRectState)
          {
          iTween.ValueTo(gameObject,iTween.Hash("from",box2Rect,"to",initialPosition,"onupdate","Movebox2","easetype","easeinoutback")); 
          }
          else
          {
          iTween.ValueTo(gameObject,iTween.Hash("from",box2Rect,"to",activePosition,"onupdate","Movebox2","easetype","easeinoutback"));
          }
          box2RectState = !box2RectState;
             
        }
         
         GUI.EndGroup();
         
         ////////////////Panel1
  
        GUI.BeginGroup(menu1Rect, "","Panel1");
 
        if(GUI.Button(boxRect,"","Panel1Button")) 
             
        {    
             
         audio.PlayOneShot(PlanetMenuSound);
  
          if(menu1RectState)
          {
          iTween.ValueTo(gameObject,iTween.Hash("from",menu1Rect,"to",initialPositionMenu,"onupdate","MoveMenu1","easetype","easeinoutback")); 
          }
          else
          {
          iTween.ValueTo(gameObject,iTween.Hash("from",menu1Rect,"to",activePositionMenu,"onupdate","MoveMenu1","easetype","easeinoutback"));
          }
          menu1RectState = !menu1RectState;
             
             
          if(boxRectState)
          {
          iTween.ValueTo(gameObject,iTween.Hash("from",boxRect,"to",initialPosition,"onupdate","Movebox","easetype","easeinoutback")); 
          }
          else
          {
          iTween.ValueTo(gameObject,iTween.Hash("from",boxRect,"to",activePosition,"onupdate","Movebox","easetype","easeinoutback"));
          }
          boxRectState = !boxRectState;
             
        }
         
      GUI.EndGroup();
  
     }
     
     //Panel 2
     void MoveMenu2 (Rect newCoordinates){
        menu2Rect=newCoordinates;
  
     }
     
        void MoveBox2 (Rect newCoordinates){
        box2Rect=newCoordinates;
  
     }
     
     
     //Panel 1
        void MoveMenu1 (Rect newCoordinates){
        menu1Rect=newCoordinates;
  
     }
     
        void MoveBox (Rect newCoordinates){
        boxRect=newCoordinates;
  
     }
     
 
 }