Symptoms: Sharp abdominal pains. Just kidding. The blinkers blink faster, or you know, you won't see it lighting up.
If you don't want to figure it out yourself, all you have to do is ask somebody at Autozone or Advanced Auto Parts which type of bulb you need, based on which make or model you have. If you have a basic vehicle, you DO NOT need the ultra premium lights. Once you have the bulbs, you can usually pop lights out of the back of the housing, and (with the car turned off), unplug the old bulb. Slide the new one in, and you're good to go.