First, locate your dipstick. Most use a metal or plastic ring, often yellow, as a grip. Carefully remove the implement from its shaft, then wipe it clean with a cloth or tissue.
Insert the dipstick back into its shaft, and push it down to the starting position. Wait a few seconds, then remove it again. Look near the bottom of the dipstick: if the top of the oil level appears beneath the lower mark, add one quart of oil to your engine.
If oil levels are too high, or if they're normal but the oil pressure light stays on, call a mechanic. The oil on your dipstick should appear smooth, glossy, and somewhat transparent. If you see dirt, sludge, brown bubbles, or a crusty brown residue, your oil needs to be changed entirely.
Next, you may need to place a phone call. Use your cell phone if you have one, or a call box if it's near and safe to walk to.
If you've been in a collision, call the police.
If your vehicle catches fire, but it is not the result of a collision, and there are no injuries, call the fire department immediately.
If your car breaks down without injuries, a collision, or a fire, you may need to call your insurance company, a tow truck, or another automobile rescue service.