Take the boat from the MK to Fort Wilderness. It will stop at the Wilderness Lodge first, just stay on. When you get off the boat you'll walk with the crowd off the marina. Walk straight ahead with the larger buildings on your right side. Those are the famous Trail's End restaurant and Pioneer Hall which houses the long-running HoopDeDoo dinner show. Continue on past those buildings to the bus stop. At the bus stop you will want to watch for an internal bus--orange Outpost or yellow Outpost. Ask each bus driver if he is going to the Campfire program. When one says yes, get on. The driver will announce the stops. Before you get off at the right stop, ask to be sure if it the correct one and ask which way to walk (you can be coming from two different sides of the campfire area). The bus drivers are very helpful and the 'purple pants' will steer you right!
Allow enough time to get there in case you have to wait for a boat, bus, or have to stop at the really cool new playground right by the marina!
Have fun!