Photon - How to do a map selection ?

So I am working on a project that uses PUN and so I want to know how to do a map selection because I want my game to have multiple maps but I don't know how to do it. If anyone helps me, it would be very nice. :) (Also, i want to use a dropdown in the creation of the room and after that, there is a list of players where the host can press 'PLAY' to start the match for ALL players in the selected map)

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 
 public class CreateRoom : MonoBehaviour 
 {
     [SerializeField]
     private Text _roomName;
     private Text RoomName
     {
         get { return _roomName; }
     }
 
     [SerializeField]
     private Toggle _privateToggle;
     private Toggle PrivateToggle
     {
         get { return _privateToggle;  }
     }
 
     public bool IsPrivate = false;
 
     public byte PlayerMax = 4;
 
     public Text RandomRoomNameText;
     private string randomRoomName;
     public string theRoomName;
     public byte sceneToLoad;
 
     public void OnClick_CreateRoom()
     {
         RoomOptions newRoomOptions = new RoomOptions() { IsVisible = IsPrivate, IsOpen = true, MaxPlayers = PlayerMax };
         newRoomOptions.customRoomProperties = new ExitGames.Client.Photon.Hashtable();
         newRoomOptions.customRoomProperties.Add("map", sceneToLoad);
         newRoomOptions.customRoomPropertiesForLobby = new string[] { "map" };
 
 
         if (PhotonNetwork.CreateRoom(theRoomName, newRoomOptions, TypedLobby.Default))
         {
             print("Verification accepted");
         }
         else
         {
             print("Verification failed");
         }
     }
 
     private void OnPhotonCreateRoomFailed(object[] codeAndMessage)
     {
         print("Failed to create a room: " + codeAndMessage[1]);
     }
 
     private void OnCreatedRoom()
     {
         print("Room succesfully created");
     }
 
     private void Start()
     {
         randomRoomName = "Room " + Random.Range(1, 999);
     }
 
     void Update()
     {
         RandomRoomNameText.text = randomRoomName;
 
         if(PrivateToggle.isOn == true)
         {
             IsPrivate = false;
         } else
         {
             IsPrivate = true;
         }
 
         if(RoomName.text == null)
         {
             theRoomName = randomRoomName;
         }
         else
         {
             theRoomName = RoomName.text;
         }
     }
 
 }