DOCBOOK: A couple of questions... DocBook's basics and documentation

Hello everybody,

With the occasion of this first message I introduce myself.
My name is Andrew and I am a programmer.
I've been asked to write a docbook visual editor( that may become
open-source ) but I never dealt with XML before so... would you please point
me to a *good* basic documentation that will allow me to get acquainted with
these things quickly?
Hoping in your ( possibly in english please ) answers, I greet you people
warmly.

Best Regards,

Andrew