IEnumerator

public void Start() // This can be public or private void whatever you want as long as it isn't taken I use start since it runs when the game starts.
    {
        StartCoroutine(Wait()); // This is how to start the IEnumerator Remember that Wait should be whatever you name it.
    }

    IEnumerator Wait() // You can name it whatever you want like Test as long as it isn't taken already
    {
        Debug.Log("Start!");
        yield return new WaitForSeconds(3); // 3 is the seconds it waits.
        Debug.Log("Done!");
    }