age restriction for itunes

I am trying to set up an itunes account for my son but I accidentally entered his birthdate instead of my own. Now, itunes won't let me create an account. How can I fix this? I am the only one who will have access to this account but I need him to have his own itunes so my intunes content for my device doesn't load onto his ipod. I want to keep his itunes content and mine separate. How can I set up a new account?