Minor Description
In the page http://incubator.apache.org/sling/site/discover-sling-in-15-minutes.html , just below the topic "Start the Launchpad", it asks to navigate to the directory launchpad/launchpad-webapp.
But there is not a directory named launchpad-webapp inside the launchpad directory. But it has a directory named "webapp", for which the instructions given in the page works fine.
So this has to be modified.