Creating Pause Game Menu

I am trying to create a pause game menu but I have two issues at this point. The first one is I cant get it so that when I press the "P" key it opens it then when you press it again it closes it. The my last problem is I am using UnitySerilizer and I cant get the load buttons this part of the code:

 foreach(var sg in LevelSerializer.SavedGames[LevelSerializer.PlayerName]) 
                         { 
                            if(GUILayout.Button(sg.Caption)) 
                               { 
                                  LevelSerializer.LoadNow(sg.Data);
                                   Time.timeScale = 1;
                               } 
                      } 

to show below my last button.

Here is the full script I have up to this point.

 using UnityEngine;
 using System.Collections;
 
 public class GrassPause : MonoBehaviour
 {
     
     public GUISkin Box;
     public GUISkin Box2;
     private string box;
     public string gameName = "Your Game";
     
     bool showPaused = false;
     
     void Update ()
     {
         if (Input.GetKeyDown(KeyCode.P))
         {
                 showPaused = true;
                 pause();
                 
         }
         
     }
     
     void pause ()
     {
         if (showPaused)
         {
             showPaused = false;
             
         }
         
         if(!showPaused)
             
         {
             showPaused = true;
         }
         
     }
     
     
      void  OnGUI ()
     {
         if (showPaused)
         {
     
             GUI.skin = Box;
             if(GUI.Button(new Rect(392,275,200,55),box))
                 {
                        LevelSerializer.SaveGame(gameName);
                 }
     
     
         //GUI.skin = Box2;//This is my load button GUI Skin
     //if(GUI.Button(new Rect(392,337,200,55),box))//This is my load button
         
         
                 foreach(var sg in LevelSerializer.SavedGames[LevelSerializer.PlayerName]) 
                         { 
                            if(GUILayout.Button(sg.Caption)) 
                               { 
                                  LevelSerializer.LoadNow(sg.Data);
                                   Time.timeScale = 1;
                               } 
                      } 
         }
  
      }
 }