first thing you need to do is go to google and do a search for:
PHP, APACHE, MYSQL
Find a good tutorial that shows you how to install the three and that makes sense to you.
Download the three from the appropriate locations and then start learning the language.
A good book for beginners is called "Instant PHP4 by Walker, Cox, and Anders published by McGrawHill / Osborne.
It walks you through creating an entire online store with examples and pictures. The examples are easy to understand.
But if you are looking for the cheap way to learn... go to google and type in "php for beginners" after you have installed everythign first.