I want to change my billing information to Chile. How can I do it?

Hey AJBehnamnia,

First, you'll want to make sure your account's country is correct:

Sign in to the account for the iTunes Store region you'd like to use. Tap Settings > iTunes & App Stores > Apple ID: > View Apple ID > Country/Region.

Then, to change your payment information, you'll do the same - except after View Apple ID, you'll do the following:

1. Enter your Apple ID password.
2. In the Edit section, tap Payment Information.
3. Update the information that you want to change.
4. Tap the Done button when you're finished.

via: iTunes Store: Changing your payment information

http://support.apple.com/kb/HT1918

and

iOS: Changing the signed-in iTunes Store Apple ID account

http://support.apple.com/kb/HT1311

Welcome to Apple Support Communities!

All the best,

Delgadoh