With your current setup it does not matter what URL is used to access the application, it will always result in the same response. So let's fix that now.
I will use [FastRoute](https://github.com/nikic/FastRoute) in this tutorial. But as always, you can pick your own favorite package.
Alternative packages: [symfony/Routing](https://github.com/symfony/Routing), [Aura.Router](https://github.com/auraphp/Aura.Router), [fuelphp/routing](https://github.com/fuelphp/routing), [Klein](https://github.com/chriso/klein.php)
By now you know how to install composer packages, so I will leave that to you.