Debian uses a Sys-V like init system for executing commands when the system runlevel changes – for example at bootup and shutdown time.

If you wish to add a new service to start when the machine boots you should add the necessary script to the directory/etc/init.d/. Many of the scripts already present in that directory will give you an example of the kind of things that you can do.

You can use update-rc.d to manage run time scripts.

update-rc.d example_service defaults