How to make an Ubuntu package with system V init script?

As the title says I want to make a ubuntu package that people could download with apt and I would like to set up the package with a System V script so that people can start and stop the service (like mysql). I've already read this article https://packaging.ubuntu.com/html/packaging-new-software.html but it too basic and didn't fully understand it, How do I tell the packager in wich folders goes what? I'm a little lost and I would appreciate any help. Thanks. This guide is really helpful https://blog.serverdensity.com/how-to-create-a-debian-deb-package/ Also here is the proper documentation that the guide is using https://wiki.debian.org/Packaging/Intro?action=show&redirect=IntroDebianPackaging