Need a menu to pop up

Hey, I know this is a stupid question but I was wondering how to make it so that say if I click the spacebar a menu appears.

It is really simple. Here's a simple code to make a box appear and disappear when the user hits the space button.

private var active1 = false;

function OnGUI () {
     if(Input.GetButtonDown("Jump")) {
          active1 = active1 ? false : true; //if true make it false and vice-versa.
             //let's the user toggle it on and off.
     }

     if (active1) { //only display the box if the user hit space.
          GUI.Box(/*Rect, "Pop up box", style*/);
     }
}