If you have an email address, please log on the site and go to http://www.greenfoot.org/scenarios/5719. Start the scenario and browse right to my link and supply me with it. I had made some major changes to the scenario (without changing the main idea). I will send it to you and you can review it to see how I managed to do things (such as adding objects from the world; creating a wall; and, making movement code with obstacles) .
2013/3/24