This 185-page book teaches the WP macro language and how to write AppleScripts for WP.
It does not duplicate the Macros Manual that comes with WP. That is a far more extensive reference, while this Scripting Guide may better facilitate learning how to program. If you've never done programming and would like to try (it's fun), this is a good place to start.
New in this version: fixed a font embedding problem in the PDF. Thanks to Ed Mendelson for pointing it out.
Free in the Files section here, as Scripting Guide 1.0.2.pdf.sit.