For auto cars, use only one leg (usually the right).
To go: engage gear to Drive, gently step on accelerator to pick up
speed, then accelerate more.
To stop: shift leg from accelerator to brake. As an auto car relies
only on the brake to stop, unlike a manual car where you can lower
the gears, brake earlier than you would in a manual car. Then shift
to Neutral (optional).
To reverse: engage Rverse gear, car should start moving so need not
accelerate alot.
It takes awhile to get used to driving an auto car if you learned
manual, so practise and good luck! 
