How do you replace tappet gasket on opel astra?

To replace the tappet gasket on an Opel Astra, first, ensure the engine is cool and disconnect the battery. Remove the valve cover by unscrewing the bolts and carefully lifting it off. Clean the mating surfaces, then place the new tappet gasket in position before reattaching the valve cover and tightening the bolts to the specified torque. Finally, reconnect the battery and check for any leaks after starting the engine.