So here's the deal, there's this guy and he's really stupid, and has ruined my invisionfree site. He has his own invisionfree site and I want to destory the site/cripple it. But to do so, I need to get into the Admin CP. And I need his password, can someone reccommend me a program or something that can help me accomplish this?

I am a complete MORON when it comes to hacking, so go slowly. I don't want to do anything complicated. Just hack his account/the admin cp to his website.