What would be the best way?

Celebrities are always signing autographs,
it has even become a hobby for some people to collect autographs. I want to get an autograph from Jessica Alba. But I don't know how to get it. I am working on this portrait of Jessica Alba, it's probably the best portrait i've done so far. And I get it, she's blowing up right now, and everyone is paying attention to her, so I can see why it would be a difficult thing to find her. Actually, I have never gotten anyone's autograph before, but I want her to put her autograph on my painting - it would be very cool. How do I do this?
Keep your eyes out for more Art and stuff from me, Brandon Uriarte.Peace