Storing and displaying info from textfield

I'm not sure what you are going for in this question, but here is some modified code. It move the bid amount to 'previousBid' and displays that amount when the close button is clicked:

 #pragma strict 
  
 private var rect: Rect;
 var btnTexture : Texture;
 private var guiOn = false;
 var ClosePostion : Vector2 = new Vector2 (200,5);
 var CloseSize : Vector2 = new Vector2 (35,35);
 var CloseIcon : Texture;
 var bid : String = "";
 var bidPostion : Vector2 = new Vector2(200,30);
 var bidSize : Vector2 = new Vector2 (50,30);
 var previousBid  = "";
 var showPrevBid = false;
  
 //opens gui
 function OnMouseDown()  {
     guiOn = true;
     rect = Rect(Input.mousePosition.x,Input.mousePosition.y,300,100);
        yield WaitForSeconds(100);
          guiOn = false;
 }
  
 //gui to display    
 function OnGUI(){
     if (guiOn){
        GUI.Box(Rect(0,0,200,200),"bids");
          if(!btnTexture){
           Debug.LogError("assign a texture");
               return;
         }
  
         //close button
         if (GUI.Button(Rect(ClosePostion.x,ClosePostion.y,CloseSize.x,CloseSize.y),CloseIcon)) {
             guiOn = false;
             previousBid = bid;
              showPrevBid = true;
         }
         bid = GUI.TextField (Rect (bidPostion.x, bidPostion.y, bidSize.x, bidSize.y), bid, 25);
     }
     
     if (showPrevBid) {
         GUI.Label(Rect(30,300,100,50), previousBid);
     }
 }