how to wait in c#

dataGridView1.Rows[x1].Cells[y1].Style.BackColor = System.Drawing.Color.Red;
dataGridView1.Refresh();
System.Threading.Thread.Sleep(1000);

void Start()
{
    StartCoroutine(waiter());
}

IEnumerator waiter()
{
    //Rotate 90 deg
    transform.Rotate(new Vector3(90, 0, 0), Space.World);

    //Wait for 4 seconds
    yield return new WaitForSeconds(4);

    //Rotate 40 deg
    transform.Rotate(new Vector3(40, 0, 0), Space.World);

    //Wait for 2 seconds
    yield return new WaitForSeconds(2);

    //Rotate 20 deg
    transform.Rotate(new Vector3(20, 0, 0), Space.World);
}