how could I spend US$ 0,28, the balance in my account, to change the country account ???

Purchase something that costs more than US$0.28, and let iTunes charge the remainder to your credit card.

it dosnt work with me as i have only 0.01 $ , it says that i have insufficient credit

it dosnt work with me as i have only 0.01 $ , it says that i have insufficient credit

Add a credit card to your account to absorb the rest of the charges.