If you want to visit the United States you must first obtain a visitor visa unless you are from one of the visa waiver countries that are exempt from this requirement.
B-1/B-2 Visitors for business (B-1) or pleasure (B-2)
These visas permit foreign nationals to visit the United States for business or pleasure temporarily for short periods of time, but do not authorize employment in the United States. The B-1 visa allows foreign nationals to conduct business associated with international trade or commerce, such as attending meetings or conferences, and negotiating contracts. Nationals of certain countries are eligible for visa waiver, which allows them to visit the United States for 90 days without having to obtain a visa.