so i want to know how to build a surveillance DVR rig
this being my example
Newegg.com - eSecure ES036883 16 Channel H.264 Level EZ Wizard DVR w/ 8 IR Bullet Cameras
looking at the most "mysterious" piece out of the collection i guess is the dvr.
how and what are the steps, hardware, and software i need to learn and purchase all the pieces and parts to manufacture my own dvr?