You must have a student visa to study in the United States and apply for one of the two options: F visa or M visa, depending on the type of school you plan to attend. 

Generally, if you are seeking studies in a university or College, High School, Private Elementary School, Seminary, Conservatory; any other academic institution including training program and vocational or other recognized nonacademic institution, you would need an F Visa. Vocational or other recognized nonacademic institution requires an M Visa. 

For short periods of recreational study, a Visitor (B) visa may be appropriate

A visitor (B) visa permits enrollment in a short recreational course of study, which is not for credit toward a degree or academic certificate. Study leading to a U.S. conferred degree or certificate is never permitted on a visitor (B) visa, even if it is for a short duration.