i asked the same question and my reply was you jack up the car and find the transmission drain plug and drain it(like an oil change) and replace it with honda transmisison fluid. and there is no filter to change. bought a manual the other day and it said the same thing. the important thing is to use a new washer for the drain plug and don't overfill it, because remember there is still fluid in the there even after you open the drain plug.
Buy honda ATF, for automatics you need 2.9 quarts. Drive the car for a little bit to get the fluid hot to help remove sediment and junk from the transmission. Put the car on jackstands, and their is a drain plug on the transmission. Loosen and take out that bolt, let the fluid drain completely into a container, and then but the drain plug bolt back in. Lower the car, and new transmission fluid in through the dipstick hole in the engine compartment. Start up the vehicle, and shift it through all the gears, (without driving anywhere). Turn the car off, and recheck the fluid level on the dipstick, add fluid if necessary to bring the fluid level up the crosshatched marks on the dipstick.
If the transmission has not been serviced on a schedule, or has never been keep your old fluid. Automatic transmission need to have the fluid changed when recommended. They can build up a film on the parts internaly that have meshed together over time. If you change it after say 80,000 miles and it has never been flushed then you wash away that build up and can create problems. In some cases thats not always true, but if it has not been flushed/changed before, or you dont know when it was done last from a previous owner just keep the fluid as is. If there is nothing wrong with it, then dont fix it.
Edit: Just realized that this was brought back from 4 years ago.