How do I create a popup below the visible element?

I am working on replacing window.open () notification system and think I can implement this with javascript.

Now I have a link that, when clicked, triggers an ajax request. The answer now appears in the popup window.open (), but instead I want it to be a div that the user can close by clicking on it. A pop-up window should appear under the link, just some kind of hint.

Can I get pointers on how to do this, or (jquery) scripts that do something like this?

Thank!