As a non-resident alien you need to file form 1040-NR ( NOT supported by TurboTax) -- please visit SprinTax ( TurboTax partner) or tax professional.
When did you come into USA and with what visa? Is this an extension? Which country ?
I came 2 years ago with F-1 visa, but I worked as student working that is allowed with my visa, so I have some Federal taxes withhold.
Since you are F-1, and have not gone past the five year exemption, you are still a Non-Resident Alien. And sin ce there is no Tax Treaty between US and Brazil ( that is listed by US Treasury ), your income for personal service is taxable income for US tax purposes. However, TurboTax does not support the form ( 1040-NR) required by Dual status or Non-Resident Aliens. Please visit SprinTax ( TurboTax partner ) or a tax professional or your school's foreign students office for help. Good luck