How to get Autograph from....?

Hi, okay I'm obsessed with Whose Line Is It Anyways, and I love the actors. So I was wondering if anyone knew how I would get Drew, Ryan, Collin, Greg, Wayne, Chip, Brad, Jeff, and possibly Heather Anne Campbell (from Improv a Ganza) ANy help is apreciated, I'm looking for addresses. I'm obbsessed. :)