How Can I Make an Instantiated Object a Child of Other Object?

Hi, what is happening is that the code that I’m using is supposed to make a transform the child of other object, but it is giving me this error an I don’t know what is wrong, can someone say me how to fix this error?

Error: “error CS1061: Type ‘UnityEngine.Object’ does not contain a definition for ‘transform’ and no extension method ‘transform’ of type ‘UnityEngine.Object’ could be found (are you missing a using directive or an assembly reference?)”

Script:

using UnityEngine;
using System.Collections;

public class Choose_Helmet : MonoBehaviour {

	public GUIText hName;
	public string helmetName;
	public GameObject helmPrefab;
	public GameObject helmSpawn;
	
	void Start()
	{
		hName.enabled = false;
	}
	
	void OnMouseDown()
	{
		hName.enabled = true;
		hName.text = (helmetName);
		var helm = Instantiate(helmPrefab, helmSpawn.transform.position, Quaternion.identity);
		helm.transform.parent = GameObject.Find("Runner").transform;
	}
}

void OnMouseDown()
{
hName.enabled = true;
hName.text = (helmetName);
GameObject helm = Instantiate(helmPrefab, helmSpawn.transform.position, Quaternion.identity) as GameObject;
helm.transform.parent = GameObject.Find(“Runner”).transform;
}