Look for a boarding school that offers a course in the performing art that you want to study. You can approach schools like Idyllewild in California or Walnut Hill in Massachusetts directly or contact The Association of Boarding Schools (TABS) to find an institution that meets your requirements.
Research the entry requirements and the application process for your chosen course. Also look at your chosen school's boarding selection criteria. Some schools will allocate accommodation to students who are offered a place on one of their courses on a first-some-first-served basis while others will consider personal circumstances and how far you live from the school grounds. There's also the not inconsiderable matter of your school fees. Many boarding schools currently charge in excess of $50,000 per year, although you may be able to apply for financial aid depending on your circumstances.
Attend one of the school's open days to get a taste of what it offers students. Talk to former and current students and teachers about the quality of the course you're considering to establish whether it's going to take you where you want to go artistically. Make sure that the boarding facilities on offer are going to be right for you. Ensure that you're going to get the space you require to work in. If you need peace and quiet, don't opt for a shared room or a dormitory.
Complete the application process in plenty of time. This could consist of various stages. After completing your initial application form, you're likely to have to submit examples of your work, complete an essay or perform an audition. You may also need to submit references and attend an interview. Make sure you've allowed yourself adequate time and space to complete all aspects of the application process to the best of your ability as competition for some schools can be intense. Indicate on your application that you would like to board at the school of your choice. Some institutions offer courses to both boarders and day students.
Move into your new lodgings once you've accepted a place. If your parents or friends can't help you move in with the belongings you'll need for your stay, consider hiring a man with a van or a moving company.
Immerse yourself in the culture and community around your particular art. Boarding at a performing arts school will give you an invaluable opportunity to learn your craft and make important contacts for your future career.