I want to take acting classes and work as a waitress at the same time. I need to know wich US visa allows both work and study. Please help me. Thank you.

A working visa is only applied for when a non resident has an employer wishing to sponsor them, otherwise you apply for a six months visitor's visa only allowing you to stay for that particular time. The visitors visa is at the discretion of the immigration officer interviewing you at the time of entry. Which isto say you may not be allowed to stay the whole six months.

Thank you for the information.

A working visa is only applied for when a non resident has an employer wishing to sponsor them, otherwise you apply for a six months visitor's visa only allowing you to stay for that particular time. The visitors visa is at the discretion of of the immigration officer interviewing you at the time of entry. Which isto say you may not be allowed to stay the whole six months.
I heard that visitors are not authorised to work/study.

Students can work on campus only, limit at 20 hours/week.