Selective overlay and expose with tooltips

I want to show my first-time users different functions of my web-app. To do this, I w开发者_StackOverflow中文版ant to make an in-page tutorial that will guide the users through different parts of the page.

I would like to use tooltip modals with instructional content. When the modal is showing, the page element in question will be exposed while the rest of the page is darkened. When the user presses "next" on the instructional modal, another set of instructions will show up and another part of the page will be exposed and the rest of the page will still be dimmed.

What's the best approach to take for this? Please advise. thanks!

jQuery Tools expose should take care of that nicely.