Turn the fan off. Wait for the blades to stop rotating.
Step up on the ladder. Look for a vertical slide switch on the wire housing of the fan, above the fan blades, if you have a newer fan. Turn this switch to the opposite direction. If you're successful at changing this switch, you're finished; you have reversed the control on your ceiling fan.
Remove the fan blades if there is no switch or the switch does not work. Unscrew the screws that attach the wooden blades to the metal rotation arms attached to the fan housing.
Turn over each fan blade 180 degrees so that the blade tilts in the opposite direction. Reattach the blades to the metal rotation arm with screws, tightening each one.
Turn your fan back on. Although it will move the same direction, the fan blades are reversed, which will reverse the air flow.