Celtic Heroes

How the hell do I use this?

I recently received an iTunes giftcard and figured I'd buy some plat with it, but can't find a place to turn cash into plat.
FWIW, I have an apple ID, and usually buy plat by inputting my PW from the item shop ingame. Any guidance is appreciated.

Apples' knowledgebase article about how to redeem iTunes gift apples: http://support.apple.com/kb/HT1574

Perfect.thanks.

Now i just need a plat sale.