The following is a very incomplete list of some of the DocBook resources on the net:
The Linux Documentation Project's DocBook Demystification HOWTO provides a good introduction to DocBook. It doesn't pull any punches.
The Linux Documentation Project's Author Guide is a good introduction to the use of the LDP XSL to produce quality HTML documentation. We are trying to stick to its guidelines, such as accurately showing command prompts, in our documentation.
DocBook - The Definitive Guide Is the reference manual for DocBook. This is accurate for the current release of DocBook. For those the want a printed manual, DocBook - The Definative Guide is available from O'Reilly & Associates. It corresponds to release 3.1 of DocBook.
Although most Linux systems seem to have enough of the DocBook tool set installed to handle our documentation, Windows does not. A complete installation package for Windows is available at the E-Novative web site.
DocBook, itself, requires lots of pieces to run. The DocBook Tools web page seems to have a rather complete step by step recipe to install all the pieces needed for DocBook in systems that do not have it installed already.