Using a user created gameobject in another scene !

Hello everyone !
thank you all for your useful helps in advance !

I wanted to know that, how I can use a user created gameobject in another scene ?
like user creates a building shape and can use it in other scene ?
I found these but didn’t help much !

 // Use this for initialization
void Start () {
DontDestroyOnLoad (transform.gameObject);
}
// Update is called once per frame
void Update () {
}

 public class CarScene : MonoBehaviour {
public GameObject selectedCar;
 
void Update() {
//Perform update logic here.. i.e. changing the selected car, etc.
}
 
void OnGUI() {
if(GUI.Button(<Rect>, "Select")) {
DontDestroyOnLoad(selectedCar);
Application.LoadLevel(<string>);
}
}
}

Create a GameManager class or Car class whatever you want to call it and save all cars in an array over there. Add DontDestroyOnLoad in the start function of that class and the selection of the car would stay. I guess you’re doing a system in which the player selects a car then races so if this didn’t make sense i think i have some code that does something similar which I can post.