Accordion

So I’m stuck. I’m new to Javascript. I have this site, http://games.nyls.edu/. If you look you can see the accordion in the right sidebar. I have everything working but I need it so that when you click on say “Card Sorting” the background image changes to an open state. Then when you close it it changes back to the initial background. Also when you click on any of the posts under card sorting, like “exclusive rights” that should also be a dropdown that show you the post content. Any ideas? Thanks.