How to load instances of a prefab to an array c#

Hello,
I’m trying to make instances of a prefab change their positions one at a time when a button is clicked.
my idea is to make an array of the prefab instances using find tag then use it in onClick function.
My code doesn’t work and I don’t know how to fix it. Please help

public GameObject[] balloons;
// ?? I don't know how to add the instances to the array 

public void OnClick()
	{    if (GameManager.instance.WrongButtonSelected == false && currentSelected == false)
		{
			GameManager.instance.WrongButtonSelected = true;
			currentSelected = true;
			for ( int i=0;i<balloons.Length;i++){
				Debug.Log (gameObject.name);
				transform.Translate(Vector2.up*speed*(Time.deltaTime));
				break;
			}	
		}	
	}

Thank you in advance

If you are creating these ‘instances of a prefab’ using Instantiate() in your code, you would likely be adding them to the array at the same time, like

for(int i=0;i<balloons.Length; i++)
  balloons *= Instantiate(BalloonPrefab.gameObject) as GameObject;* 

On the other hand, if these are instances you’re creating in the editor, you can drag-and-drop them into the array. Just take each of the GameObject instances from the Hierarchy panel, and drag into the public, editor-visible Balloons array, on whatever object has this script.
Now, onto the matter of your logic, I also dont think that will give the results you desire. Your for-loop, since it uses a break statement, will only ever move the first (index-0) element. I think if you tried something like this, it would give you what you want “change their positions one at a time when a button is clicked”
int index = 0;

public void OnClick() {
if (GameManager.instance.WrongButtonSelected == false && currentSelected == false)
{
GameManager.instance.WrongButtonSelected = true;
currentSelected = true;

Debug.Log (balloons[index].gameObject.name);
Vector2 moveDelta = Vector2.upspeed(Time.deltaTime);
balloons[index++].transform.Translate(moveDelta);

index = index % balloons.Length;
}
}

This should work if you set the gameobject tags correctly.

balloons = GameObject.FindGameObjectsWithTag("myTag");