如何为精灵设置动画？

I'm using Flex and AS3 to try and create a game, and I'm wondering how I can animate things easily. I would prefer to use sprite sheet images. I'm going to go a head and post the code (It's really short) I got so far, can someone look over it and tell me the best/simplest/easiest way to add animation support? Thank you in advance.I'm using Flex and AS3 to try and create a game