Now that you've got your WordPress install set up, it's time to do something with it." Naturally, you can just download a theme and the plugins you want, start tinkering, and learn by doing/hacking. That's a proven method for sure, employed all the time. It is, in fact, how I got started with WordPress way back.
However, since you ponied up for this book you may as well get a head start. This chapter is all about what makes WordPress tick. It doesn't go into depth on every file in the system, but rather serves an introduction to how WordPress works so that you gain the knowledge needed to start developing sites running on WordPress.
From here on, it will help if you know a little bit of PHP, as well as (X)HTML and CSS. If these are alien concepts to you, be sure to read up on them at least a bit. You don't need to know either one by heart, but some sort of understanding is definitely needed.
WordPress is written in PHP, a popular scripting language used online. You probably know this, and if you're even the least bit knowledgeable in PHP you'll quickly find your way around WordPress and the various functions it offers on the plugin and theme development end of things. That being said, you don't need any prior PHP experience to do funky stuff with WordPress. Granted, you won't be able to create WordPress plugins without knowing PHP, but you can certainly make things happen with the built-in template tags used in themes, and that will ...