DirectInput offers a complex API. You do not want to learn the complete API because you just want to use the steering wheel in your XBAP WPF game.
There is a simple yet powerful wrapper for joystick style devices, developed in C# by Mark Harris. We can use it to obtain values from the steering wheel. There is an example Windows Forms application that can help us to understand how to work with this wrapper.
The source code is available as part of the code that can be downloaded for this book. ...