Isometric Survival Shooter Tutorial - How do I add jump?

I just completed the excellent tutorial for creating an isometric shooter. I really want to build on this and the first thing I'd like to do is add the ability to jump.

I looked up jump code and I tried to implement it but I'm new so I'm doing it wrong. For example, in the tutorial PlayerMovement.cs there's the public class PlayerMovement : Monobehavior. The code I found for adding jump has the public class `using UnityEngine. This is my code from the tutorial:

 public class PlayerMovement : MonoBehaviour
 {
     public float speed = 6f;
 
     Vector3 movement;
     Animator anim;
     Rigidbody playerRigidbody;
     int floorMask;
     float camRayLength = 100f;
 
     void Awake()
     {
         floorMask = LayerMask.GetMask("Floor");
         anim = GetComponent<Animator>();
         playerRigidbody = GetComponent<Rigidbody>();
     }
     void FixedUpdate()
     {
         float h = Input.GetAxisRaw("Horizontal");
         float v = Input.GetAxisRaw("Vertical");
 
         Move(h, v);
         Turning();
         Animating(h, v);
     }
 
     void Move (float h, float v)
     {
         movement.Set (h, 0f, v);
         movement = movement.normalized * speed * Time.deltaTime;
 
         playerRigidbody.MovePosition (transform.position + movement);
 
     }
 
     void Turning()
     {
         Ray camRay = Camera.main.ScreenPointToRay (Input.mousePosition);
         RaycastHit floorHit;
 
         if(Physics.Raycast (camRay, out floorHit, camRayLength, floorMask))
         {
             Vector3 playerToMouse = floorHit.point - transform.position;
             playerToMouse.y = 0f;
 
             Quaternion newRotation = Quaternion.LookRotation(playerToMouse);
             playerRigidbody.MoveRotation(newRotation);
         }
     }
 
     void Animating(float h, float v)
     {
         bool walking = h != 0f || v != 0f;
         anim.SetBool("IsWalking", walking);
     }
 }

The code I'm trying to merge is:

  using UnityEngine;
  using System.Collections;
  
  public class Jump : MonoBehaviour {
      public bool grounded = true;
      public float jumpPower = 1;
      // Use this for initialization
      void Start () {
          
      }
      
      // Update is called once per frame
      void Update () {
          if (Input.GetButtonDown("Jump") && grounded == true) {
              rigidbody2D.AddForce(transform.up*jumpPower);
              grounded = false;
          }
          }
  
  
  }

I realize the jump code needs to set grounded back to true to make it work correctly but I figured I'd address this as an extra step once I got the basic code working.

I have tried to merge the code two different ways but, as expected, I received errors in both instances. Any help would be greatly appreciated!

Thank You!