To measure voltage on a battery for example you first turn your meter to DC Voltage. Place the red probe on the positive terminal of the battery and place the black probe on the negative side of the battery or on a common ground. Your voltage will display on the screen.
As your engine turns, the camshaft pushes your breaker points open, which creates a high voltage induction in your ignition coil. This high voltage power runs through your spark plug igniting your engine. Residual electricity in your ignition coil’s primary circuit is absorbed by the condenser.