How is this done?

Hey friends :O)

I have a question…I’m working on this interactive map and as you can see in these thumbnails (click on the thumbs for a larger view) I’mnot sure how i would do this. In the first picture the user will click a button and a picture of the clinic will appear…as you see in the 2nd thumbnail.

There’s a button that says “close” i’m not sure how to make the clinic picture dissapear. Any suggestions? thanks u sooo much!:+)