How to put a password on itunes when it first comes up?

I'm super controlling when it comes down to my things. I'm to the point where i'm extremely angry because my entire family has an IPhone and an Ipad its so freaking annoying. I had gotten my Iphone and then my Ipad and now my sister, mom and dad has one… My dad doesn't even know how to work a computer and still has an ipad and don't even know how to work that. I'm just fed up and I dislike my sister I don't want her touching all the music I bought with my hard paying money… So how can I put a restriction on her IPad where she can't connect nor can she synchronize it. Please help. Right now I've set a passcode to my shared library…

Just go to settings, general then pass code resctriction you can enter a 4 digit code to get onto the device or even a longer password, also you can lock some of the apps like photos and turn photo stream off in settings you can google some simple things if you need more help!