There is an XML file included inside the XML folder, but that will upload the content (posts, pages, etc) but it doesn’t load widget areas (not sure why). I saw mentioned in another thread that they were going to use a plugin to export everything so users can import the widgets.
Adding content inside of the widgets can be done by dragging whichever widget you want into a widget area. They’re using text widgets for the demo, so use one of those and add some text/html and thats pretty much it.