To find the number one spark plug, you must consult your vehicle's repair manual or a reliable online resource specific to your engine (e.g., 3.8L V6, 5.7L V8, LS1 V8). These resources will show you a diagram of the engine with the firing order clearly marked and the location of each spark plug.
Do not attempt to locate the spark plug by guessing. Misidentifying the cylinders can lead to engine damage.