Park the two cars close to each other, and locate the batteries and terminals. Bring out your jumper cables and attach one of the red clamps to the battery's positive terminal that's not working. Take the second red clamp and connect it to the positive terminal of the good battery. Attach one black clamp to the negative terminal of the working battery and attach the second black clamp to a metal surface on the engine of the car that's not working. When the revived car starts, remove the cable by detaching the negative clamps first, then the positive.