CS0120 error

Hi guys. I'm new to unity and was trying to make a roll a a ball game just to try and get some basic understanding of the program. I have been watching a tutorial on how to make the game and have followed the instructions as closely as i can but still cant manage to get the first lot of coding quite right for some reason. i think its something to do with the "player controller" at the to. this is the coding i have so far

using UnityEngine; using System.Collections;

public class PlayerController: MonoBehaviour {
void FixedUpdate () { float moveHorizontal = Input.GetAxis("Horizontal"); float moveVertical = Input.GetAxis("Vertical");

     Vector3 movement =new Vector3 (moveHorizontal, 0.0f, moveVertical);
     Rigidbody.AddForce(movement*10.0f);
 }

}