Presentation is in /presentation/presentation.html.
App is in /app. Use 1.8.7 or fix requires - OSX is 1.8.7 by default, as is, I belive, cygwin. You'll need to install RubyGems if you're using Ruby < 1.9.
cd /app
rvm use 1.8.7
gem install sinatra
ruby site.rb
localhost:4567 to see the app.