When you have first setup your iTunes account and tried to make purchased from the iTunes Store, you had to supply valid credit card information other form of payment method, and enter your full billing address details. You can of course change your credit card information from iTunes itself, but you are also able to update your payment information from an iPad, as explained in this tutorial.
Update billing information from your iPad
Follow these steps to change credit card or payment information:
Click on the "Home" button of your iPad to find the "Settings" icon in one of your Home screens, then tap on it.- When your iPad Settings open with the "General" options preselected, tap on the "Store" category on the left.
- Then, tap on the "View Account" button at the top, and your iPad will display a "Sign in Required" message; tap on the "Continue" button to proceed and enter your credentials.
- After typing your password, tap on "OK", and the "Edit Account Info" popup will open.
- Tap on the "Payment Information" button to view and edit your credit card details.
- If needed, edit your credit card information and/or billing address; once you are done updating your payment method, tap on the "Done" button in the "Edit Billing Address" popup's top right corner.
- Your iPad will return to your iTunes Store settings screen.
Tip: for your protection and security, your iPad (and the iTunes Store) will automatically timeout your session. In other words, if you stay with the Edit Billing Address dialog open for too long without doing anything, you will receive a "Your session has timed out. Please try this operation again from the beginning" error message; all you need to do is tap on "Done", start over from the top of this tutorial, and then edit your payment information as soon as the screen opens.
This is all it takes to update your credit card and other billing / payment information from the iPad!