become an administrator account?

Someone in my family has the admin account and won't tell me the password or make me an admin. I've been trying to find tricks to get admin rights but on Windows 7 Ultimate, it is a lot harder... (on Windows 7 all I had to do was log into safe mode, create a new account with admin rights, and then change my account to an administrator.) Apparently people are saying that there is a default admin account on Windows 7 Ultimate and I've tried typing in the cmd "net user administrator /active:yes" but it doesn't appear? I think it's because the admin account my family member has is the default one and changed it so there's a password? Are there any other tricks to becoming an admin?

(I might have not put enough information because I don't know much about computers, if there is any information need to help me, just ask :P)

Sorry but helping you bypass family restrictions on your PC would be against forum rules.