Students from abroad studying in the U.S. are non immigrants and have an F-1 Visa. Under this visa, they can work for less than about 20 hours on campus including any place on the university campus, like a cafe. Most of the on-campus jobs are posted on the university portal for graduate/undergraduate students. The links for applying are given there itself. You just have to check the skills required, your available working time and few other things and then apply for the best suitable job. Sometimes, seniors might help in finding you a job, so keep good contacts with your seniors in the university.