I know this is an old post, but it went unanswered.
A stepper motor does not have position feedback (unless you add it). So it relies on the stepper never missing a step, and the Arduino keeping track of how many pulses it has given to move, and in which direction.
The pminmo link gave me a 404 error, so I just went there and looked for 6560:
If that link doesn't work, do like I did.
However, I see there may be a problem with using that chip without buffering. There is an Instructables on using the TB6560AHQ with a 74HC14 schmitt trigger/inverter to buffer the incoming signals and ensure they are clean. It includes both the Eagle files and the board pattern as an image so you can just hand wire it with the image as an aid.
This page talks about problems encountered using a 3 axis board with TB6560AHQ without the inverter/schmitt, and how he solved it using the 74HC14.