The home page in the demo is set up as a slider and the some widget areas underneath – http://www.redfactory.nl/themes/therestaurant/2011/06/22/frontpage-widgets/
Visual Composer doesn’t work 100% with the restaurant theme as it isn’t based on bootstrap, it uses its own custom framework. Still with some css tweaks some people have managed to get it working, see – https://support.redfactory.nl/forums/topic/visual-composer-2/
To get the home page to see the visual composer content you’ll need to go to reading>settings from the wp admin area and change the home page to a static page, not ‘latest posts’. http://screencast.com/t/9Evb0gKsM
If you’re working on the back end of the page with visual composer, make sure you save the changes and republish prior to reviewing the page.