The seating plans for Boeing 747 passenger aircraft differ based on the airlines operating them. Seat maps can be viewed by visiting the airline's website, such as United.com, or by reading the information pamphlet in the seat-back pocket of the aircraft itself.
Another option is to visit SeatGuru.com, which has a comprehensive listing of all the seat maps used by different major airlines. A similar easy-to-navigate website is SeatExpert.com. Alternatively, if you have already booked a flight, SeatMaestro.com can find the seat map for your aircraft. For those interested in history, vintage seat maps for a variety of aircraft including the 747 are archived at Frequently Flying.