I'm only a few steps ahead of you, but I think I might be able to give you some insight I've picked up along the way.
PHP and MySQL are a great mix for people getting started in dynamic web development in my opinion. Getting a good book is a great way to start. I have one (I forgot the title and it's sitting at home). Also, finding tutorials and bits of code online will help you clean up your own code and give you a grasp of standard logic structures or whatever. I did things a little backward and started reading tutorials before I bought a book. I think if I had started with the book, I'd be a lot more efficient coder right now.
As for the forum you were talking about, look into getting some already developed web applications, such as
phpBB. Putting together a forum takes a lot of work and knowhow. Getting something like phpBB will help you understand what's happening, how the PHP scripts are setup, how they interact with one another, how PHP calls on MySQL, etc.
There are also packages for Blogs, but since I'm not a big fan of blogs, I haven't looked at them much.
Also, a big thing that I'm just beginning to do is planning out my website. Know which pages will connect to which pages and when (ie when a user has the right authentication level). From what it sounds like what you want to do, you'd need a publicly accessable index page that would display the latest information you've added. You'd also need a private (ie password protected) section where you could log in to insert new data into a MySQL database, edit old entries, and delete old entries. Something to that degree.
Best of luck my man. It's a lot of fun (at least for me).