how can used my gift card?

No.

The gift card is only valid for the country of purchase.

If you can’t redeem your iTunes Gift Card or code

http://support.apple.com/kb/HT6021

Redeeming iTunes Gift Cards and content codes

http://support.apple.com/kb/ht1574

Purchasing an iTunes Gift Card for use in another country

http://www.ilounge.com/index.php/articles/comments/purchasing-an-itunes-gift-car d-for-use-in-another-country/

 Cheers, Tom 😉