Your book will probably have to skim over the higher principles of OOP, and to fully grasp them in order that you get the maximum benefits that OOP offers you will buy many more books (unless you are a secret Will Hunting).
Certainly learn the syntax of OOP in PHP 5.3 if you are in learning mode.
You can start using PHP to write scripts without using OOP, but can gradually add it in order to "simplify" or shorten your scripts.
I think the easy wins in adopting OOP in PHP are encapsulation and complexity hiding, grab these low hanging fruit.
Make sure you fully adopt PDO if you can because this forces you to use objects, and PDO is an ideal base class to start hiding things and including them as and when you need them.
You will see threads on here about building on PDO too.
You have to absolutely nail the syntax and best use of functions though before even thinking of their equivalent in OOP (methods). If you are extracting complexity and repetitive code as functions, and putting them in their own files and including them as a matter of course as you work (note: not as you learn) then you will switch to OOP with far greater ease, and it should make much more sense to you.