Following tutorial "roll-a-ball" and there are errors

I am fallowing the roll a ball tutorial (9:40)and am getting the error below when I try to run the game. I know c++ pretty well and I'm trying to jump right into unity using my general programmer knowledge. I have no previous game engine experience.

error:
Assets/Scripts/PlayerController.cs(21,27): error CS0120: An object reference is required to access non-static member `UnityEngine.Rigidbody.AddForce(UnityEngine.Vector3, UnityEngine.ForceMode)'

code:

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class PlayerController : MonoBehaviour {
5.  
6.     // Use this for initialization
7.     void Start () {
8.     }
9.    
10.     // Update is called once per frame
11.     void Update () {
12.    
13.     }
14.  
15.     void FixedUpdate(){
16.         float moveHorizontal = Input.GetAxis ("horizontal");
17.         float moveVertical = Input.GetAxis ("Vertical");
18.  
19.         Vector3 movement = new Vector3 (moveHorizontal, 0, moveVertical);
20.  
21.         Rigidbody.AddForce (movement);
22.     }
23. }
24.  

 

Shouldn't that be:

Code (CSharp):

1.  
2. rigidbody.AddForce(movement);
3.  

 

or something like this for Unity 5 >>:

Code (CSharp):

1. GetComponent<Rigidbody>().AddForce(movement*speed*Time.deltaTime);

 

or ..
Predefine a variable and use it in subsequent Updates.

Code (CSharp):

1.     private Rigidbody rb;
2.  
3.     void Start ()
4.     {
5.         //Declare the rigidbody within the script
6.         rb = GetComponent<Rigidbody>();
7.     }
8.  

 

Thanks, I think I'm getting closer So I have this now:

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class PlayerController : MonoBehaviour {
5.  
6.     Rigidbody rb;
7.  
8.     // Use this for initialization
9.     void Start () {
10.         rb = GetComponent<Rigidbody>();
11.     }
12.    
13.     // Update is called once per frame
14.     void Update () {
15.    
16.     }
17.  
18.     void FixedUpdate(){
19.         float moveHorizontal = Input.GetAxis ("horizontal");
20.         float moveVertical = Input.GetAxis ("Vertical");
21.  
22.         Vector3 movement = new Vector3 (moveHorizontal, 0, moveVertical);
23.  
24.         rb.AddForce (movement);
25.     }
26. }
27.  

But when I run it I'm getting this error:
ArgumentException: Input Axis horizontal is not setup.
To change the input settings use: Edit -> Project Settings -> Input
PlayerController.FixedUpdate () (at Assets/Scripts/PlayerController.cs:19)

I went to edit > project settings > input, and It looks like everything is set?

 

Try "Horizontal" in place of "horizontal"