stepper motor? how to program?

how to control stepper motor with its certain range/ distance to operate, just for example in watering system with conveyor using 3 soil moisture sensor.i want to identify a certain range where the stepper motor navigate horizontally with the conveyor with the water sprinkler only in 1 sensor that has only detects the low level of moisture. the project is base from the design of farm bot. im newbie in arduino and i want to learn more about that stuff.

Start by looking at http://forum.arduino.cc/index.php?topic=284828.0 and get familiar with controlling the stepper.

thanks