Please note that a Study Permit for high school studies is not acceptable for University study.
In Canada as a Visitor?
Students who are already in Canada as Visiting and Exchange students (for only 1 term - with visitors status) can apply for a CAQ and Study Permit from within Canada should their exchange be extended to 2 terms (thus requiring a CAQ and Study Permit). Please see "Applying for a Study Permit from within Canada" on the Immigration Canada website for details and for other categories of visitors who are eligible for this option.
Visitors who do not meet the criteria outlined in the above website will have to apply for a Study Permit at a Canadian Visa Office outside Canada. Consult "Get a study permit" section of Immigration Canada’s website for more information.