How do you change the transmission fluid on a 2003 Honda Accord?

Get a 3/8" ratchet with a 3/8" extension. A drain pan, and the appropriate amount of Transmission Fluid.

Underneath the vehicle, on the passenger side, look at the bottom of the transmission. There is a drain plug there, not a bolt. The 3/8" ratchet (With extension) should fit right in that hole. Move your catch pan under there, and pull the plug. Once it stops draining, replace the drain plug washer and re-install the plug. Top off your transmission fluid, and run the car to check it for leaks. Be sure to dispose of the used transmission fluid accordingly.