Public string/GameObject not in inspector

using System.Collections; using System.Collections.Generic; using UnityEngine;

public class OnTriggerLoadLevel : MonoBehaviour { public GameObject guiObject; public string levelToLoad;

 private void Start()
 {
     guiObject.SetActive(false);
  
 }


 private void OnTriggerStay(Collider other)
 {
     if (other.gameObject.tag == "soda")
     {
         guiObject.SetActive(true);
         if (guiObject.activeInHeirarchy == true && Input.GetButtonDown("Use"))
         {
             Application.LoadLevel(levelToLoad);
         }
     }
 }


 private void OnTriggerExit()
 {
     guiObject.SetActive(false);
 }

}