To get aquainted with PHP it's useful to think of a little project you want to realize in PHP. That will give you something to focus on and apply what you've read in manuals/tutorials directly to a real-world-problem. Probably a guestbook or a feedback form serve as good beginner projects.
And your book is quite right; PHP is about programming. You don't really "design" a page in PHP, you rather design it like you do a normal HTML page, and only at specific sections of that page you insert small PHP parts, which help with producing the desired HTML output.
For instance, you could have a <div> with a guestbooks's entry date in it. With PHP, you write a script that puts out a number of <div>s ordered by the date within. Just as an example.