Check your car's automatic transmission fluid monthly! This will take a few minutes, but will increase the lifetime of your vehicle considerably. Just watch this automotive video tutorial to see how to check and add transmission fluid in your car.
Park your car on a level surface and start the engine, leaving your gear in neutral or park, unless instructed otherwise in your vehicle's owner's manual. Find the ATF dipstick located at the back of the engine. It looks a lot like the engine oil dipstick, but is shorter and usually red. Pull it, wipe the dipstick off, put it back in fully and take it out to check the fluid levels. You might need to add a bit of transmission fluid if it is low.