How to animate elements when you scroll down?

Hello,

How can I animate elements when I scroll down?

I know this can be done with ScrollMagic.io but I can't seem to understand how I can solve my problem with this plugin.

So basically what I want is to have a background image and when you scroll down, the background stays there and over it elements show/hide based on the scroll position.

Any idea?

Thanks, Klevis