How to connect a 6 volt component to an xbee?

Electronics newbie here. I’d like to connect a model train smoker (6 volt) to my xbee. Why can’t I just wire in series a second 3 volt battery to bump the output from the xbee to 6 volts? Will I fry my xbee? A guy at Radio Shack wrote a circuit for me that has a transistor and a resistor that I wrote up here: and I wondered if I needed those components?

Yes it will. You need to use a level shifter to do that instead.