This page presumes you have gone through the Get Started page and have successfully installed Xamarin Studio, Xcode, and all the requisite libraries. If you're ready, let's get the HelloRhino app building on both iOS and Android. Then we can look at how all the pieces fit together to share code between the platforms.
Mac OS X step-by-step instructions
Windows 8.1 step-by-step instructions
Warning: This section is a work-in-progress: Information may be missing or incomplete.