further explanation of Wh- questions: http://learnenglishteens.britishcouncil.org/grammar-vocabulary/grammar-videos/question-words
more examples: http://engcouncil.blogspot.it/2012/05/1-why-want-to-know-about-reason-of.htmlhttp://engcouncil.blogspot.it/2012/05/1-why-want-to-know-about-reason-of.html