SHOWCAST and AT2 advice please!

Hi all, I'm a lurker who hasn't ever really posted, but was hoping for a bit of advice. My agent asked me to sign up to both Showcast and AT2 and I have...but now I'm unsure of how to use them. I understand that casting agents now have easier access to my profile on searches...but is there anything pro-active I can do on each site? I think I've got the hang of using 'pitch' option on AT2 but I don't really understand how to use Showcast. None of the uses for each option is very clear to me and they don't seem to have an FAQ! What's the best way to make the most of the money I've just spent? Any help would be appreciated! Thanks guys. Max