Define "use"? It runs every time you turn the radio on or play a DVD. It should be playing through the surround speakers. Are you referring to using those speakers instead of TV speakers for over the air channels?
I know there is a post here on how to do it...but it will take me longer to search then just repost the link.
PLEASE do not send questions via Private Message, my inbox fills up too quickly. Post questions in the forum as a new thread so that other users can benefit from the answers. Use Private Messages for sensitive information only (VIN, Contact info or things you do not want the public to see).