how to fix unexpected symbol 'MonsterPrefab' error CS1525 for a tower survival game

I tried using this code in c sharp script but could not get the script to work. It always kept saying ,"Assets/PlaceMonster.cs(8,52): error CS1525: Unexpected symbol 'MonsterPrefab', expecting '(',')',',',';','[','{', or '' using UnityEngine; using System.Collections;

public class PlaceMonster : MonoBehaviour {

 // Use this for initialization
 void Start () {
         new GameObject MonsterPrefab;
         new GameObject Monster;
         
         private bool canPlaceMonster ()
     {
             return Monster == null;
         }
         //1s
         void OnMouseUp ()
         {
             //2
             if (canPlaceMonster ()) {
                 //3
                 Monster = (GameObject)
                     Instantiate (MonsterPrefab, transform.position, Quaternion.identity);
                 //4
                 AudioSource audioSource = gameObject.GetComponent<AudioSource> ();
                 audioSource.PlayOneShot (audioSource.clip);
                 
                 // TODO: Deduct gold
         }
     }
 }

}

Please help