Use your step ladder to take down the fan blades you wish to replace on your Harbor Breeze fan by unscrewing the blade brackets from the motor or flywheel. Set aside the two screws that hold each blade bracket in place. Repeat the process for all of the blades.
Detach each blade from its respective blade bracket by unscrewing the three screws that connect the blade to the blade bracket. Repeat the process for all of the blades.
Attach the first replacement blade to a blade bracket using three screws. Repeat the process for all of the blades. Ensure that the screw holes are in the identical places as on the blades you took down.
Reattach the blade bracket to the motor or flywheel using two screws. Repeat for the other three blades.