If you want to travel free country in America, you need a Visa !!!

Visa America Travel

About

1. Register online and make an appointment to make a US visa with the Embassy.

If you are applying for a visa from other countries, you only need to prepare the document and bring it directly to the Embassy to submit, to apply for a U.S. tourist visa, the first thing you need to do is to make an appointment with the Embassy in advance. . The appointment is made after you have paid the visa processing fee.
First, you access the link http://www.ustraveldocs.com/vn_en/vn-niv-ds160complete.asp to fill in the required information, then you will be assigned 1 Bank to close charge.
Once the payment has been completed and your bank’s confirmation is complete, continue to visit https://www.ustraveldocs.com , register for an account, then log in and schedule an interview with the Ambassador bar.
After the appointment has been successfully booked, the Embassy will also designate a post office for you to send your US travel visa application to the Embassy via post.

US Embassy visa