This image demonstrates what I need to achieve: http://i.imgur.com/JEtfwvt.png

I need those blue widgets opening inside the browser, say, when I hover above some elements in the webpage. They need to hold some HTML. I am far from being an expert in web development, and I don't know how to proceed. What is a reasonable way to implement the widget entities? Modal windows probably won't work, since they block the parent page; tooltip that would open multiple windows sounds like a stretch too.

What directions should I investigate?

Thanks a bunch.