What are the specifications of your stepper motors? There are lots of ways to skin this cat, and I think we would need more details on what kind of cat you are dealing with.
Stepper motors work on pulses. Pulses correlate with angle. The pulse frequency determins the speed. So if 1 pulse = 1 degree then 360 pulses would equivalent to turning the motor 360 degrees. If you send 360 pulses in 1 minute, you would be rotating the motor at 1 rpm.
Some stepper motors have controlling hardware built into them and you communicate with them through some kind of serial communication protocol. In this scenario you would send a command to the motor controller telling it what you want it to do.
A solution will need to be tailored to your specific hardware (there is no generic "stepper motor" solution, but I suspect that you will probably need to use at least 1 counter for encoder feedback).
