Getting a Visa

All foreign workers must obtain permission to work legally in the United States. Each employment category for admission has different requirements, conditions and authorized periods of stay.  There are five categories on The Official Website of the Department of Homeland Security that relate to getting a visa to work in the US.  These categories are for: Temporary (Nonimmigrant) Workers, Permanent (Immigrant) Workers,  Information for Employers and Employees; and Temporary Visitors for Business.

http://www.uscis.gov/working-united-states/working-us