Without knowing the details of your stepper driveres and motors it's a little hard to give good advice.
But you should probably do something like this:
you should NOT try to power the steppers from Arduinos supply. The Arduino board can not supply the amount of current the motors need, and will probably go up in smoke if you try. You need a seperate power supply for the motors.
-hook the supply voltage for the motors up to the drivers
-connect the Arduinos ground to the drivers ground
-connect two digital (output) pins from arduino to the step and direction inputs on the driver.
-check the stepper library thats somewhere on this website.
You would be better of if you have the details of the motors, like supply voltage, current consumption, and steps pr. rotation.
And the same goes for the drivers, especially how much current they can handle? enough for the motors ?