Michael Schoch, Answers questions on Noodle
High Schools don't typically issue visas to students. You can learn about applying for a student visa from the U.S Bureau of Consular Affairs.
Lastly, you might find some of this more general advice on studying in the U.S. for international students.
This info should help your daughter get started on the exciting process of studying abroad. If you still feel confused or if I haven't entirely answered your question, feel free to ask a follow up question! Good luck!