How to rotate an object to face the direction it's going?

Hello, I currently have a waypoint system but I can’t seem to figure out how to make the object face the direction it’s going. This is the code for my waypoint system.

using UnityEngine;
using System.Collections;

public class Waypoints : MonoBehaviour
{
		private Transform startMarker, endMarker;
		public Transform[] waypoint; 
		private float speed = 1.0F;
		private float startTime;
		private float journeyLength;
	//	public Transform target;
		private int currentStartPoint;

		void Start ()
		{
				currentStartPoint = 0;
				SetPoints (); //Function om de waypoints in te zetten
		}
	
		void SetPoints ()
		{
				startMarker = waypoint [currentStartPoint];
				endMarker = waypoint [currentStartPoint + 1];
				startTime = Time.time;
				journeyLength = Vector3.Distance (startMarker.position, endMarker.position);
		}
		void Update ()
		{
				float distCovered = (Time.time - startTime) * speed; 
				float fracJourney = distCovered / journeyLength;
				transform.position = Vector3.Lerp (startMarker.position, endMarker.position, fracJourney);
				if (fracJourney >= 1f && currentStartPoint + 1 < waypoint.Length) {
						currentStartPoint++;
						SetPoints ();
				}
                
		}
}

Try this: Quaternion.LookRotation. Look at the sample code