Unity doesn't recognise new Input system error CS0234

Hi. absolute newbie to unity and I have been having some real problems with using the new input system.

I am trying to learn how to create games on unity and so am following a Udemy video coding learning program. I first created a 2D game and when I installed the new unity imput system I would get bizarre error code that said "error CS0103: The name 'keyboard' does not exist in the current context." That was using unity version 2020.3.17f1 because of the following code:

using System.Collections; using System.Collections.Generic; using UnityEngine;

using UnityEngine.InputSystem;

public class GatherInput : MonoBehaviour { public int directionX = 0;

 void Update()
 {
     if (Keyboard.current.dkey.isPressed)
     directionX = 1;
     else if (Keyboard.current.akey.isPressed)
     directionX = -1;
     else
     directionX = 0;
 }

}

When i used a capitilisation of the letter "K" the message changed to: error CS1061: 'Keyboard' does not contain a definition for 'dkey' and no accessible extension method 'dkey' accepting a first argument of type 'Keyboard' could be found (are you missing a using directive or an assembly reference?)

So I changed to a new version just today. now version 2020.3.18f1; and after entering the above same code my error message read:

Assets/Scripts/GatherInput.cs(5,19): error CS0234: The type or namespace name 'InputSystem' does not exist in the namespace 'UnityEngine' (are you missing an assembly reference?)