Altering ExportAllStories

I'm trying to get into changing scripts already supplied with InDesign, so I can alter them myself.

But I can't for the life of me figure out how to do this.

I have the Exportallstories.jsx that came with indesign. But I want to change this so that it Exports the Story from all open documents.

But I don't have a clue where to start. I've read the Scripting Guide from Adobe, which explained somethings but was mostly confusing, and I've read another Scripting Guide and couldn't find out how to do this.

Basically I don't want the script to export all the stories from one document, but to export the stories from all open documents.

But I also need it to insert the filename for each document as the name of the document.

Where do I start?