Log onto disneychannel.com and go to Hannah Montana's home page. On the main page you will find a link to contact her. Write in the questions you would like to ask her and anything else you would like to say. Be patient as a response could take weeks.
Visit her Myspace.com page and drop a comment or leave her a message. Myspace is handy because it connects the world socially, but some pages are false and made up by people who aren't who they say they are. Be sure to get your parents' permission before visiting Myspace.
Visit Hannah Montana fan pages and post something on their message boards. Because the website is a Hannah Montana fan page you never know when she might stop by and respond to some of the questions or feedback on the discussion board.