A google search is the place to start. A search for “fritzing part unl2003” (which is the stepper driver) turns up
http://fritzing.org/projects/windows-iot-stepper-servo-and-dc-motors
on the Fritzing projects site. Downloading Motors.fzz and loading it in to Fritzing gets you the stepper driver and stepper motor in the temp parts directory. Right click on both parts and select export part to write them as an fzpz file. You now have the stepper driver and motor parts which appear to match those in the kit. I’m not sure what an additional power module is because it doesn’t appear in the parts list for the kit that google finds, unless you mean the ywrobot power supply board which is here:
http://omnigatherum.ca/wp/?p=262
You need to check the pcb footprints of the parts before ordering boards because user supplied parts are of varying quality (and sometimes just plain wrong). Print the footprint out on paper at one to one scale and try it against a real part before ordering boards. If you find parts that are broken post a link to them here and one of us will likely fix them for you.
Peter