how do i make a new ipod account?

i have the newest ipod ( the ipod 5) & my brother just got the ipod 4. we both shared the same account to start our ipods. he used to get my messages, & then it stopped because i changed my imessage account, & then my dad got my pictures on his iphone. we all share the same account. now my brother is getting my pictures on his ipod. its really annoying cuz i want my ipod stuff to only be on mine, not on my bros. its really annoying how they can read everything i say, or pretty much look at everything on my ipod. is there anyway to change it? i wanna make a new account, but you need an itunes card for it i think, & i dont have one. is there any way i cant stop it from going onto their iphone/ipod? its just so annoying. & if i can make a new account, is there a way so it wont delete any of my stuff?