The idea is to cut a part of the stem and then make it reform roots from the base of the new cutting. Once those roots are established you can plant it like you normally would. This is your new clone! With Dracaena and Cordyline (both genera of plants are closely related), you most likely will not need any extra push to create roots, but I would still use some type of rooting hormone. The rooting hormone mimics a natural plant hormone that would normally initiate new root development. The following would be how I would make these cuttings...