Problems with 2D movement Script

Hey learning how to game dev with unity and got my hands on a couple books to help. First time in doing something in C# and unity. While getting a movement script for a 2d object on a 2d plane I’m having issues getting it to compile properly. Here is what I’ve got.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class NewBehaviourScript : MonoBehaviour
{
//1
public float movementSpeed = 3.0f;

//2
Vector2 movement = new Vector2();

//3
Rigidbody2D rb2d;

private void Start()
{
    //4
    rb2d = GetComponent<Rigidbody2D>();
}

private void Update()
{
    // Keep this empty for now
}

//5
private void FixedUpdate()
{
    //6
    movement.x = Input.GetAxisRaw("Horizontal");
    movement.y = Input.GetAxisRaw("Vertical");
}

//7
movement.Normalize();

//8
rb2D.velocity = movement * movementSpeed;

}
The Compiler is having issues with the last two lines. Any assistance is much appreciated and thank you in advance you kind souls.

I think you need to have the last 2 lines in the update function . The last 2 lines will not work if they are outside of the function because of how to update function works. read here to know more: Unity - Scripting API: MonoBehaviour.Update()