help with the menu

Hi I want to create a menu .
with a label and two buttons .
The label " Select " button and the " play " " Exit" .
I would like pressing play , the label changes in " level playing " and buttons " easy " " difficult."
But I can not continue some help ?
void OnGUI()
{

    GUILayout.BeginArea(new Rect(Screen.width / 2 - 150, Screen.height / 1 - 150, 300, 350));

	GUILayout.Label("Select");
    if (GUILayout.Button("Start", GUILayout.Height(40)))
    {

    }

    if (GUILayout.Button("exit", GUILayout.Height(40)))
    {
        Application.LoadLevel("scena3");
    }

    GUILayout.EndArea();

}

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using UnityEngine;

public class test : MonoBehaviour {
	
	bool difficulty = false;
	
	void OnGUI() {
		

		if (!difficulty){
			GUILayout.BeginArea(new Rect(Screen.width / 2 - 150, Screen.height / 1 - 150, 300, 350));
			GUILayout.BeginHorizontal();
			GUILayout.FlexibleSpace();
			GUILayout.Label("Select");
			GUILayout.FlexibleSpace();
			GUILayout.EndHorizontal();
			if (GUILayout.Button("Start", GUILayout.Height(40)))
			{
				difficulty = true;
			}
			
			if (GUILayout.Button("Exit", GUILayout.Height(40)))
			{
				Application.LoadLevel("scena3");
			}
			GUILayout.EndArea();
		}

		else{

			GUILayout.BeginArea(new Rect(Screen.width / 2 - 150, Screen.height / 1 - 250, 300, 350));
			GUILayout.BeginHorizontal();
			GUILayout.FlexibleSpace();
			GUILayout.Label("Difficulty");
			GUILayout.FlexibleSpace();
			GUILayout.EndHorizontal();
			if (GUILayout.Button("Easy", GUILayout.Height(40)))
			{
				
			}
			if (GUILayout.Button("Normal", GUILayout.Height(40)))
			{
				
			}
			if (GUILayout.Button("Hard", GUILayout.Height(40)))
			{
				
			}
			if (GUILayout.Button("Back", GUILayout.Height(40)))
			{
				difficulty = false;
			}
			GUILayout.EndArea();
		}

	}
}