How do i create an options menu?

 Here is a code which all you need is to copy and paste it in c# file amd you will have a menu then attach this script to the Main Camera in the scene and you can pick if you want a background image to add to it:

 using UnityEngine;
 using System.Collections;
 
 public class Menu : MonoBehaviour 
 {
     public GUISkin guiSkin;
     public Texture2D background, LOGO;
     public bool DragWindow = false;
     public string levelToLoadWhenClickedPlay = "";
     public string[] AboutTextLines = new string[0];
 
 
     private string clicked = "", MessageDisplayOnAbout = "About \n ";
     private Rect WindowRect = new Rect((Screen.width / 2) - 100, Screen.height / 2, 200, 200);
     private float volume = 1.0f;
 
     private void Start()
     {
         for (int x = 0; x < AboutTextLines.Length;x++ )
         {
             MessageDisplayOnAbout += AboutTextLines[x] + " \n ";
         }
         MessageDisplayOnAbout += "Press Esc To Go Back";
     }
 
     private void OnGUI()
     {
         if (background != null)
             GUI.DrawTexture(new Rect(0,0,Screen.width , Screen.height),background);
         if (LOGO != null && clicked != "about")
             GUI.DrawTexture(new Rect((Screen.width / 2) - 100, 30, 200, 200), LOGO);
 
         GUI.skin = guiSkin;
         if (clicked == "")
         {
             WindowRect = GUI.Window(0, WindowRect, menuFunc, "Main Menu");
         }
         else if (clicked == "options")
         {
             WindowRect = GUI.Window(1, WindowRect, optionsFunc, "Options");
         }
         else if (clicked == "about")
         {
             GUI.Box(new Rect (0,0,Screen.width,Screen.height), MessageDisplayOnAbout);
         }else if (clicked == "resolution")
         {
             GUILayout.BeginVertical();
             for (int x = 0; x < Screen.resolutions.Length;x++ )
             {
                 if (GUILayout.Button(Screen.resolutions[x].width + "X" + Screen.resolutions[x].height))
                 {
                     Screen.SetResolution(Screen.resolutions[x].width,Screen.resolutions[x].height,true);
                 }
             }
             GUILayout.EndVertical();
             GUILayout.BeginHorizontal();
             if (GUILayout.Button("Back"))
             {
                 clicked = "options";
             }
             GUILayout.EndHorizontal();
         }
     }
 
     private void optionsFunc(int id)
     {
         if (GUILayout.Button("Resolution"))
         {
             clicked = "resolution";
         }
         GUILayout.Box("Volume");
         volume = GUILayout.HorizontalSlider(volume ,0.0f,1.0f);
         AudioListener.volume = volume;
         if (GUILayout.Button("Back"))
         {
             clicked = "";
         }
         if (DragWindow)
             GUI.DragWindow(new Rect (0,0,Screen.width,Screen.height));
     }
 
     private void menuFunc(int id)
     {
         //buttons 
         if (GUILayout.Button("Play Game"))
         {
             //play game is clicked
             Application.LoadLevel(levelToLoadWhenClickedPlay);
         }
         if (GUILayout.Button("Options"))
         {
             clicked = "options";
         }
         if (GUILayout.Button("About"))
         {
             clicked = "about";
         }
         if (GUILayout.Button("Quit Game"))
         {
             Application.Quit();
         }
         if (DragWindow)
             GUI.DragWindow(new Rect(0, 0, Screen.width, Screen.height));
     }
 
     private void Update()
     {
         if (clicked == "about" && Input.GetKey (KeyCode.Escape))
             clicked = "";
     }
 }