First of all, a major correction: the programming language you're talking about is called "PHP". What you used, "phpBB", is the name of a message board software.

As a beginning, you can read the tutorial on php.net. It will get you started. Then, dive in the manual whenever you need help! The thing is fully searchable and has a lot of useful user replies to give you some extra tips and clarification. I really can't recommend enough the manual for any question you might have on a specific function.

Unfortunately for you, there's no such thing as a Frontpage for PHP. However, once you're started, it's an easy language to pick up and learn. I did most of my training by myself, and look at the place we're exchanging messages in!