Lightbox questions based on a decision tree showed and updated in background

Hi,
 
I'd like to create a website based on a decision tree to help users in their choices. In my mind, I'd like a graph with boxes viewing all the possibilities (on the background webpage) and a lightbox showing the choosing step. After each choice, the graph will be updated to show the way and the lightbox is updated with the new question.
 
Is there an example here forthis kind of request ? Or, where can I found a example to help me inthis task please ?