This question is a derivative of this one: Creating XNA AudioEngine on windows game project
I am working from the same book, and have the same problem as the original qu
Make sure you have the reference to Microsoft.Xna.Framework.Xact.dll
In Visual Studio, in your Game project, right click on References folder -> Add Reference
Select Browse tab, and navigate to Program Files (x86)/Microsoft XNA/XNA Game Sudio/v4.0/References/Windows/x86/, select Microsoft.Xna.Framework.Xact.dll and click on OK.
Add using Microsoft.Xna.Framework.Audio;
and you should be able to use AudioEngine
class.