The outdoor and indoor units are connected by copper lines that circulate refrigerant through coils. The refrigerant removes heat, and fans blow cool air through ductwork and vents.
Central air often shares ductwork with your furnace. Use the dampers in your ductwork to control airflow to different rooms.
Get a professional inspection every year. In between, change the filter every 1-3 months and clean debris from the outdoor unit at least twice a year. Over time, the refrigerant can get low, which may require a refill (recharge).