'WH' Questions"

Question words are also called 'wh questions' because they include the letters 'W' and 'H'.

- Asking questions:

   1.If you ask about the subject of the sentence, simply add the question word at the beginning:

   Example:
   "James writes good poems." — "Who writes good poems?"

  2.If you ask about the predicate of the sentence (the part of a sentence which contains the verb and gives information about the subject), there are three options:

       If there is a helping (auxiliary) verb that precedes the main verb ( for example, can, is, are, was, were, will, would...), add the question word and invert the subject and the helping (auxiliary) verb.
       Examples:
       "He can speak Chinese." — "What can he speak?"
       "They are leaving tonight." — "When are they leaving?"

       If you ask about the predicate and there is no helping (auxiliary) verb and the verb is "to be", simply add the question verb and invert the subject and the verb.
       Example:
       "The play was interesting." — "How was the play?"

       If there is no helping (auxiliary) verb in the the predicate and the main verb is not "to be", add the auxiliary "do" in the appropriate form.
       Examples:
       "They go to the movies every Saturday." — "Where do they go to the movies?"
       "He wakes up early." — "When does he wake up?"
       "They sent a letter." — "What did they send?"
http://www.myenglishpages.com/site_php_files/grammar-lesson-wh-questions.php