These links may help, but I don't have any experience with those very small motors.
Stepper Motor Basics
Simple Stepper Code
If you use a h-bridge you will need 4 Arduino I/O pins for each motor and if you want a fast step rate for all the motors at the same time a 16MHz Arduino may not be fast enough.
Using a specialized stepper driver such as a Sparkfun Easydriver you will only need two Arduino pins for each motor and the computation load for the Arduino will be considerably lower.
...R