How to circulate fireplace heat?

We have a wood burning fireplace on our main floor. The thermostat is in the hallway connecting the room with the fireplace to the kitchen/livingroom. When we have a fire in the winter the fireplace room is a nice 75 deg but the rest of the house is cold because the furnace doesnt come on. I have tried turning on the fan because there is a return air vent in the fireplace room. Still no heat gets up stairs where our master bedroom is. Can I block the rest of the return air vents besides the one in the fireplace room? Will this help with my problem? Or, how is the best way to distribute this heat? We have three levels- unfinished basment, main level and upstairs bedrooms