help with wiring

Hope someone can take the time to help this cnc/electronics
challenged guy out. I have got together all my stuff to convert my
sherline mill to cnc. I went with gecko 210's for the drivers and am
in the process of wiring one of them up to one of my stepper motors
just to see if i can get one to work (would sure make me feel a lot
better!) I am going right down the box hooking up wires and it sort
of makes sense to me. Where I am a little confused is on the common
and current set. I belive the commong is the terminal I want to run
from pin one of my game port to get my 5v. Then there is a formula
to figure out the resistor I guess I need for the current set that
looks like this....R (in kilo-ohms)=47*Amps/(7-amps). I should have
paid more attention in math class. What amps are we talking here..my
motors are rated at 2.0 amps if that helps. Can I get a reistor like
this at radio shack? Oh am I supposed to set my jumper in my gecko
to common ground or common +5 volts when I use the game port. Thanks
for any help :)

Matt