Help About NavMeshAgent

Im creating an AI and I just need to patrol him around Please Help me to do this . Im just a Beginner in UNITY . Advance Thanks :) This is the Code of Tutorial that I Watch : using UnityEngine; using System.Collections;

[RequireComponent(typeof (NavMeshAgent))] public class chase : MonoBehaviour {

 public NavMeshAgent agent;
 public Transform player;
 public Transform head;
 static Animator anim;


 string state ="patrol";
 public GameObject[] waypoints;
 int currentWP = 0;
 public float rotSpeed = 0.2f;
 public float speed = 1.5f;
 float accuracyWP = 5.0f;
 // Use this for initialization
 void Start () {

     anim = GetComponent<Animator> ();
     agent = GetComponent<NavMeshAgent> ();
 }
 
 // Update is called once per frame
 void Update () 
 {
     
     Vector3 direction = player.position - this.transform.position;
     direction.y = 0;
     float angle = Vector3.Angle (direction, head.up);

     if (state == "patrol" && waypoints.Length > 0) {     
         anim.SetBool ("isIdle", false);
         anim.SetBool ("isWalking", true);
         if (Vector3.Distance (waypoints [currentWP].transform.position, transform.position) < accuracyWP) {

             //currentWP = Random.Range (0, waypoints.Length);
             currentWP++;
             if (currentWP >= waypoints.Length) {
             
                 currentWP = 0;
             }
         }

         direction = waypoints [currentWP].transform.position - transform.position;
         this.transform.rotation = Quaternion.Slerp (transform.rotation, Quaternion.LookRotation (direction), rotSpeed * Time.deltaTime);
         this.transform.Translate (0, 0, Time.deltaTime * speed);
     }
             
     if (Vector3.Distance (player.position, this.transform.position) < 8 && (angle < 30 || state == "pursuing")) {
         
     
         state = "pursuing";
         this.transform.rotation = Quaternion.Slerp (this.transform.rotation, Quaternion.LookRotation (direction), rotSpeed * Time.deltaTime );
 
         if (direction.magnitude > 2.5) {
              
             this.transform.Translate (0, 0, Time.deltaTime * speed);
             anim.SetBool ("isWalking", true);
             anim.SetBool ("isAttacking", false);
         } else {
             anim.SetBool ("isAttacking", true);
             anim.SetBool ("isWalking", false);
         }
     }
     else 
     {

         anim.SetBool ("isWalking", true);
         anim.SetBool ("isAttacking", false);
         state = "patrol";

     }
 }

}