[Alan Anderson]

You're using C++, a cRIO, a Victor, and a Fisher-Price motor. You want to control the speed of the motor using software? What you're asking is such a basic part of programming an FRC robot that I have to wonder if I don't understand the question.

Pretend that the software is already done and working, and describe how you want to control the speed. Try to be as specific as you can, like "pulling back a little on a joystick will make the motor run slowly forward, pushing forward a lot will make the motor run quickly backward," that sort of thing. That'll help explain more clearly what you want the software to do.