If it's about the book, would you mind posting these kind of questions here: http://p2p.wrox.com/book-beginning-a...0-18759-3-389/
Makes it easier for others to find relevant questions and answers.
That said, if they are just warnings, and everything works fine at run-time, you can safely ignore them. Visual Studio doesn't always know where the classes are defined. This is especialy the case when using themes as VS doesn't always know which theme is in effect.
The book mentions these warnings here and there, IIRC.