How do I: Make a button open a content area?

I’m currently working on a new flash site and exploring some ideas I haven’t tried yet. If you go to you’ll see the intro I’ve created which will either remain as a backdrop or just as it is throughout the operation of the site.

What I want to do with the site pages is have them appear as a semi-transparent backdrop with the contents within that area. Each time you click on a menu link it simply changes the contents with a transition or something. The main thing is I don’t want the whole page to reload, just the contents, because I don’t want to lose viewers’ focus on the page while it would otherwise go white and reload the entire page - repeating the same graphics and animations, etc. Please see for idea of what I’m going for.

You’ll notice a button called “open” in the middle of the content area. This is what will appear after the intro animation, and then the viewer can click on the button which will bring up the news or about content along with the menu.

So just to simplify what I want to do and don’t know how:

Intro (done)
Button appear
[Click button]
Open content area w/ menu
Menu links change content

It’s fairly simple and I’ve seen it done all the time, but I can’t find any tutorials anywhere. If you can help I would greatly appreciate it!