There are no internal buses for the resort. AirGoofy is correct; just ask the driver. The busses have a specific route. Typical is Grandstand - Paddock - Carrousel - Congress Park - Springs - in that order for buses to the parks. Buses to DTD are slightly reversed.
The resort is somewhat spread out, but you can walk anywhere at an easy pace in no more than 8 to 10 minutes. (Try that at Fort Wilderness!)