I do flush on mine, just watch a youtube video on flushing auto tranny. Some say don't flush, some do it religiously. Up to you, the kiatechinfo site shows a diagram of tranny with which hose is in/out to do the flush you pull the one coming from the cooler, which is "IN". It's also marked on the tranny body. Start the car up with that hose disconnected from the body and put into a large container. When you start the car it will pump out fluid, just pour in the new fluid at the same time to prevent the pump from sucking air and overheating. When the fluid coming out looks new stop. And check levels, top offf/drain to the correct level as per usual.
Some argue for/against this method. I think it gets more fluid changed out to new. Because your pumping new fluid thru the crooks/crannies of the tranny not just replacing whats in the pan. Take whichever course your most comfortable with. The pan method is just like what jcwit said. Dran pan, replace same quantity of fluid in the dipstick. Then check the level like 50 times on as flat road surface possible. I've checked sometimes and get really off levels on the dipstick.(you check ATF with car running in Neutral)