stepper motor help

hi, i need help in building a cnc machine. not the hardeware just the circuit. i already saw this https://www.instructables.com/id/EG9RXG6F54HJ7SL/ and the circuit that it included but i coulden't understand the circuit. there is this circuit http://www.aaroncake.net/circuits/stepper.asp which i have already built but need help connecting it to my parallel port on my computer. i would really appreciate it.

Aaron's site has a circuit for a parallel port interface. Cheers, Pat. Pending