newbie in need of help

hello, im new to all this. and i dont know where to begin. Im
confused as to what part of the software does what and what part of
the hardware does what. in other words, does the software send general
instructions to dedicated hardware(not the computer) that then decodes
and turns it into xyz coordinates or does the software(computer) send
individual instructions (step by step) to the stepper controller
hardware. is there a good tutorial that explains the whole constrution
from start to finish. perhaps a schematic or a sample source code?