Sorry, I’ve got no Drupal experience. So apart from a https://www.drupal.org/developers and a https://www.drupal.org/docs/8/creating-custom-modules link — where I see there’s a guide for building a “Hello, World” module — I can’t really help.
Maybe someone else here will, but your chances are probably better in a Drupal forum.
Would be great though if you can share a bit back here of what you learn.