Rooted means having root access (superuser access - akin to Administrator account on a Windows machine), which allows you to play with system functions.
Post your phone's model (you said you had an M8, but what carrier are you on? The procedure is slightly different sometimes for different carrier models) and I can pull up the instructions on how to root.
You can't really just "insert" something. You'll need to make an app or framework module (such as XPosed) that allows you to stop/restart/start services and such.
You can use the Android Emulator that comes with the SDK to play with things rather than risking your phone, as well.
