How can you sing the Star Spangled Banner for the Oakland A's?

I am been wishing to sing the Star Spangled Banner for one of the Oakland's A's games and I want to know how I can have the chance to do so. It has been my dream to sing at one of their big games when they host teams such as Boston, Tampa Bay, New York, and San Francisco. If you can help me, then I will be the happiest person in the world :)