Turn off the main power if possible
Verify the circuit is de-energized with a tester
Remove the panel cover
Identify the breaker to replace
Turn the breaker to the off position
Disconnect the wire from the breaker
Release the breaker from the bus bar
Remove the breaker from the panel
Install the new breaker in the same slot
Reconnect the wire to the new breaker
Snap the breaker onto the bus bar
Reinstall the panel cover
Turn the main power back on
Turn on the new breaker
Test the circuit to confirm it works