Your car's headlights are one of the most important pieces of safety equipment on the vehicle. If one or both of the bulbs have burned out, you may be fined by the police—or worse, end up in a collision. Fortunately, changing your car's headlight bulbs is a fairly easy task. It's also a lot cheaper than asking a mechanic to do it for you.
It's a good idea to check your car's headlights once a week or so. And do it in the daylight—you don't want to get caught out at night with a burnt-out bulb. Even in daylight, the check is as easy as turning them on and looking at them. Finding out what type of replacement bulb to use isn't much harder. Check your owner's manual first. If you can't find the information there, you can find it at your local auto-parts store. You'll need to know the year, make, and model of your vehicle. Or just bring in the burnt-out bulb and match it to a new one.
Note: This tutorial is for lights found in halogen systems, where the bulb is loaded into the back of the lens. If your car has sealed-beam headlights, this won't help (but that job is super easy, too—any good car repair manual for your make and model will tell you how). If your actual headlight glass needs to be replaced along with the bulb, that's an easy fix, too, as is replacing a bad tail light or turn signal.