How do I perform a toilet tank gasket replacement?

To perform a toilet tank gasket replacement, first turn off the water supply to the toilet. Drain the tank by flushing and soaking up any remaining water. Remove the tank bolts and lift off the tank. Replace the old gasket with a new one, ensuring it is properly seated. Reassemble the tank and tighten the bolts. Turn the water supply back on and check for leaks.