How do you change spark plugs on a BMW z3 1.9?

To change the spark plugs on a BMW Z3 1.9, first, ensure the engine is cool and disconnect the negative battery terminal. Remove the engine cover if necessary, then carefully detach the ignition coil or spark plug wires from each spark plug. Using a spark plug socket and ratchet, unscrew the old spark plugs and replace them with new ones, tightening them to the manufacturer's specified torque. Finally, reconnect the ignition coils or wires and the battery terminal before starting the engine.