I think I am confused in a different way now. The link shows the use of an easy driver stepper motor driver board (which is likely to be an excellent choice) but you seem to be thinking of using an L298 driver board which is primarily intended for DC motors and is a poor choice for driving a stepper motor. It is more complicated to connect to the Arduino and it doesn't allow you to drive the motor with high voltages. The easydriver will have a small potentiometer that you adjust to set the maximum current to suit your motor.
Have you asked Google if it can find details for your motors?
It would be useful to know the maximum current that they can take. And since you know the coil resistance the nominal voltage would enable you to calculate that - if you can find that somewhere.
How many wires are connected to your motors? 4 or 6 wires is likely to make the motor easier to use than 5 wires.
You will need to measure the resistance between the different wires to figure out which wires belong to which coils.
...R