showing post description on hover

I have my posts set up on the home page with just the thumbnail showing and I want the description (i.e. title, category, excerpt, etc.) to show when hovered over. I’m picturing this done with jQuery where the background darkens and the div containing the post description changes its style from display:none to display:block. Problem is I’m not sure where to start. Any helpful advice would be appreciated.

Also, I’d rather not use any plugins for this.