Controlling 2 wire stepper motor via Arduino

My boss gave me an exhaust cutout motor for my truck. He said he had already replaced the motor due to "clicking" noises, but I think that the cheap board was unable to correctly control the motor because the motor stopped clicking when partially opened and removed from power, then when power was re-applied, it would not fully close. It is a board with two buttons that when one or the other is pressed, would either open or close the valve, letting exhaust by-pass the muffler, letting it get louder and reducing back pressure for racing. The motor appears to be a two-wire design. I want to set up an Arduino with a potentiometer set in my dash so I can use it to control the amount that the cutout is open. Where do I start? I know how to set up an H-Bridge.... Any pointers would be appreciated....

Also, I don't know much about coding besides what I've gleaned from examples. Please, nobody do it for me, I love the thrill of discovery. But, I need to know where to begin with code as well. There is a mud race in two weeks and this will give me a bit of an advantage...

What your describing sounds like the MotorKnob example, where the stepper will follow the pot as it rotates. You can use the map function to show the degree of rotation on a display.