You should be able to do it yourself, log into your account (e.g. by tapping on your id at the bottom of the Featured tab in the App Store app on your iPad) and put your US billing address on your account : Change the country of your iTunes Store, App Store, iBooks Store, and Mac App Store account
You won't be able to change your country on your account if you have a balance on it, or if you have unexpired rentals or season passes.
Dear sir/lady<br/>I would like to change the country on my apple id from malaysia to u.s.a .<br/>Is there a problem of doing this change,<br/>Please reply to my request.<br/>Sincerely yours,<br/>Pegah mirjafari<br/>[<br/><br/>Sent from Yahoo Mail for iPad | https://overview.mail.yahoo.com?.src=iOS]
There shouldn't be a problem in changing it, and you should be able to do it yourself (we are fellow users here on these forums, we can't change it for you)