Turn off the water supply if needed
Place a bucket under the sink
Disconnect the P-trap and drain tailpiece
Remove the old drain flange from the sink
Clean the sink drain opening
Apply plumber’s putty or sealant to the new drain flange
Insert the new drain flange into the sink opening
Tighten the drain assembly from below
Reconnect the tailpiece and P-trap
Tighten all slip nuts securely
Wipe away excess putty or sealant
Run water to check for leaks
Tighten connections if any leaks appear