Confused--help???

[dzny72]

Okay--I am basically putting this out there and hoping someone can 
explain better than what I have seen so far.  I just reread DH and am 
still not getting how Draco ended up being the "rightful master" of 
the Elder Wand, and how it recognized that Harry had taken Draco's 
original wand.  I have tried to read posts (only of OTC) and I am 
still confused.  Can someone either explain by pointing out specific 
parts in canon or direct me to a post that does so??
Thanks!!

Dzny