Matrix user forums

Hi All, I am building a stepper motor driver board using a pic 16f876a and so far have written a flowcode chart which steps the stepper icon and reverses direction via a toggle switch. This will of course be the direction signal from the mach3 software. I can step through the program using F8 and all works perfectly. My question is how do you get the program to step from the input pin (B0) Being a stubborn type I have bent my head for some time before asking for some help. Any assistance will be really appreciated.
Many thanks
Les