Creating pop up form with dark background
So, I'm trying to learn how to create a form that that
1) pops up
2) isn't a window that can be moved
3) and doesn't make me leave the current page.
4) Provides a darkened transparent background drop that hides the content on the current page.
I just need some direction on what I should be looking at to accomplish this. I looked at this page, but I think I still need more info.
Any suggestions on where I can start to learn how to do this?