Logo graphic in header

["Roger Weinheimer" <RogerW@onyx.com>]

I need some high level information on how to put a graphic logo in the
header for an article. I would like the logo to appear at the top of
every page of published output (html and pdf) in the area where the
prev/next links and article title appear.

I'm just looking for a pointer to the pertinent documentation or maybe
an overview. Does it involve setting a parameter? Modifying a template?
Creating a customization layer? I'm not sure what to call it in docbook
terms. I've looked in the tdg and tcg and haven't seen anything that I
recognize as pertinent.

I appreciate any suggestions.