Theres 2 ways to do this, first electricaly change the connections, and secondly if the stator (bit with windings on) is a seperate piece then you can take the motor apart, reverse the stator and put it back together, and the motor will run the other way.
The other way is to alter the windings, I'm assuming its a single phase motor, you have to reverse the supply to the start winding with respect to the run winding, the start winding often has a start capacitor in series with it.
The wires will be colour coded and maybe the terminals will be letter coded, unfortunateky the codes here in the uk will be diffo, ours are red and black and 'A' and 'AZ' for run winding, yellow and blue and 'S' and 'T' (amongst others) for start.
What are the colours of the wires going into the windings, and whats marked on the terminals?, a photo inside the terminal box might also be usefull to us.