Business courses in high school may help you determine your interest in the subject, but are not required or expected for frosh business majors in college (since many high schools do not have such courses).
Otherwise, follow the usual high school base curriculum: http://talk.collegeconfidential.com/high-school-life/2055289-faq-high-school-college-prep-base-curriculum.html
(Within IB, take math SL or HL, not math studies SL.)