You should attach Patrol.cs to Enemy

Meanwhile you should create way points manually or by using WaypointCircuit.cs script

Below i attached screenshots of InspectorView. Based on that you can arrange your enemy characters.

//Patrol.cs using UnityEngine; using System.Collections;

public class Patrol : MonoBehaviour {

   public Transform[] points;
     private int destPoint = 0;
     private NavMeshAgent agent;
     //public NavMeshAgent agent2;
     Animator m_Animator;
     public Transform target;
     void Start () {
         agent = GetComponent<NavMeshAgent>();
         //agent.updatePosition = false;
         // Disabling auto-braking allows for continuous movement
         // between points (ie, the agent doesn't slow down as it
         // approaches a destination point).
         agent.autoBraking = false;
         m_Animator = GetComponent<Animator>();
         GotoNextPoint();
 
     }
     
     
     void GotoNextPoint() {
         // Returns if no points have been set up
         if (points.Length == 0)
             return;
         
         // Set the agent to go to the currently selected destination.
         agent.destination = points[destPoint].position;
         
         // Choose the next point in the array as the destination,
         // cycling to the start if necessary.
         destPoint = (destPoint + 1) % points.Length;
     }
     
     
     void Update () {
         // Choose the next destination point when the agent gets
         // close to the current one.
         if (agent.remainingDistance < 0.5f)
             GotoNextPoint();
 
 
         if (hero.erun == true) {
             m_Animator.SetBool ("run", true);
             agent.speed = 3;
             transform.LookAt(target);
         } else {
             m_Animator.SetBool ("run", false);
             agent.speed = 2;
 
         }
 
 
         if (hero.eattack == true) {
             m_Animator.SetBool ("attack", true);
             agent.speed = 0;
             //agent.updatePosition = false;
             //transform.LookAt(Vector3.zero);
         } else {
             m_Animator.SetBool ("attack", false);
             //agent.speed = 2;
             //agent.updatePosition = true;
         }
 
 
     }
 
 
 }

Enemy Character Inspector Screenshot :-