You can password-protect apps like iTunes so that a family member can't buy every U2 record with your credit card. Go to Settings, then General, then Restrictions.
Press Enable Restrictions and type a password, then turn on the restrictions you want for the apps available.
Note that this password is different from your iTunes password - you'll need to tap in both.
"iPad Tips and Tricks : Password protection "
Reference : top-ipad-video-converter.com