Turn off the water supply valve behind the toilet
Flush the toilet to empty the tank
Hold the flush lever down to drain as much water as possible
Remove the tank lid and set it aside safely
Disconnect the flapper chain from the flush lever
Unhook the flapper ears from the overflow tube pegs
Remove the old flapper
Match the new flapper to the old one
Attach the new flapper ears to the overflow tube pegs
Connect the chain to the flush lever
Leave a little slack in the chain
Turn the water supply back on
Let the tank refill
Test the flush
Adjust the chain length if needed
Check for leaks and proper sealing