This document discusses how to set up the Windows Phone SDK 7.1 to develop applications for Windows Phone Mango (7.5). It covers installing Visual Studio, the Windows Phone SDK 7.1, and creating a basic "Hello World" PhoneGap application to test that the environment is set up correctly. Key steps include downloading and installing Visual Studio Express for Windows Phone, installing the Windows Phone SDK 7.1, and using a PhoneGap project template within Visual Studio to build a simple application with "Hello PhoneGap" displayed.