RigidBody Cube Movement

I have been learning unity for 2 days now and I decided to make an empty project to see what I've learnt in the past 2 days and I ran into a problem where if I hold down on of my WASD keys I am not able to keep the cube moving it just stops moving after a click, but I want it to continue moving until I stop holding on of my WASD keys. Any help would be appreciated

Here is my code:

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

public class Move :...

RigidBody Cube Movement