In order to be eligible for employment in the United States, non-citizens will need a visa that authorizes employment.
International students who have an F-1 Student Visa are eligible to work while studying and for a period of up to fourteen months after graduation. There is also a J-1 Exchange Visa that allows visitors to work for up to four months.
The best route for international job-seekers is to apply for the appropriate visa though one of the placement agencies listed below. Note that there is typically a fee required for placement, which varies by agency.