the stepper is moving at a constant speed when the number is 0.1, 0.2, 0.3 ... and so on but at a 0.0 or 1.0 its not moving..?
I still have no idea what number you are talking about. Nor do I have any idea what code is running on the Arduino. Stepper firmata is not part of the standard (but not supported) Firmata library.
Post a link to where you got that sketch, and define what number you are talking about. How is that number supposed to make the stepper step? What is 0.3 steps supposed to look like? How do you expect a PWM pin to make a stepper step? The on/off times are pretty fast for making a stepper step.