How am I able to PUT SOUND

using UnityEngine;
using System.Collections;

public class DiEps : MonoBehaviour {

void Update () {
	System.DateTime threeHrsFromStart = System.DateTime.Now.AddMinutes(3);
	if (System.DateTime.Now - threeHrsFromStart > System.TimeSpan.FromMinutes(3)){

		//I need to place here a sound. How am I able to call it in here.

It will be somehow, like an alarm clock. after the time ends it will ring.



You attach an audio source component to your object, set the relevant options and then call audio.Play();