Changing credit card information on iTunes - Apple iPad (16 GB) WiFi Tablet PC

You don't actually put it on the tablet. You sign into your itunes account from your tablet, then scratch the back of the card to reveal the serial number and type that into the itunes account and your money will appear on your account as a credit for you to make purchases. have fun.

Credit of what sir? Itunes Gift card? can you clarify more> Thank you.

Log in to your account for apple store. go to accout
edit credit card info. Change or remove your payment information from your iTunes Store account...

Had that problem too. Call the Kindle (Amazon) service number.

Start by installing iTunes on your computer.
Then create an Apple Account through iTunes.
See Store in top menu.
You will need an Email Address and Credit Card.
iTunes is your interface to buying Apps, Songs etc
as well as Backing Up & Recovering your iDevice Apps & Software. As well as installing updates e.g. the New IOS8

Good Luck
Cheers
TJ

you need to buy an apple itunes voucher in a shop or online to load your apple ID account.
If you already have an Apple ID that you use with the iTunes Store, App Store, iBooks Store, or Mac App Store, you can redeem your gift card without using a credit card.
Redeem your code on iPhone, iPad, or iPod touch

1. Tap iTunes Store, App Store, or iBooks Store on your device.
2. Scroll to the bottom of the Featured section and tap Redeem. You will need to sign in with your Apple ID.
3. Tap "You can also enter your code manually."

Apple and iTunes Gift Cards Apple Store
Redeeming iTunes Gift Cards and content codes

When you are setting up an iTunes (Apple) account you don't need a credit card.
See the link:
Creating an iTunes Store App Store iBooks Store and Mac App Store...

Go to iTunes store and click redeem. You'll type in the code and your balance should appear. I think you might still need a credit card on file, though...