If you are looking to be a massage therapist, check the requirements for certification with the appropriate state agency, usually through the attorney general's office. Then check the local yellow pages or other directories (on- of off-line) for schools that teach those skills in your area. Before enrolling, check with state agencies and agencies such as the Better Business Bureau to ensure the schools are legitimate, that their graduates pass state certification exams, and that they have been able to find jobs in their field after graduation. Usually these programs are offered by proprietary schools, many of which operate nation-wide.

If you are talking about other types of spa treatments (manicurist, facialist, etc.), you may need the same kind of training as a beautician. Again, look to the same two sources given above to locate reputable schools.  

If you are talking about the management end ofl the business that does not require certification in specific types of treatments, you are looking at some kind of business degree or certificate. If the spa is one of many owned by the same company, see if the company has any kind of management training program. Even if it does not, determine the qualifications they expect of management personnel. Then check out local colleges and proprietary schools to find the appropriate degree/certificaton program for business management. 

In addition, use your time to cultivate skills that are essential to any of these positions. Work on your communication skills, your people skills, your professionalism. As someone once said, "Act and dress the position you want in the company, not the position you have." Essentially, that means to show your employers that you have the capability of being more than a valet and that you desire a long-term relationship with the company.