Start the visa extension as early as possible. Canada requires that you submit an extension application 30 days before your current visa expires, which is the date stamped on your passport.
Download, or request in writing, an application package from Canadian immigration. This provides a guide for extending your visa and an application.
Make sure that you are eligible to extend your visa in Canada before you pay the application fee, as this fee is non-refundable.
Complete the application. The form is officially called an "Application to Change Conditions, Extend My Stay or Remain in Canada" (Form IMM1249). The link providing access to the PDF file is cic.gc.ca/english/pdf/kits/forms/IMM1249E.PDF.
Pay the application fee and get the original receipt of payment (Form IMM5401). You can pay online and then print the form, or take the form with you to a bank and pay in person.
Mail the completed application and all necessary documents, including receipt of payment to: Citizenship and Immigration - Visitor Case Processing Centre, 6212 - 55th Avenue, Unit 303, Vegreville, ABT9C 1W1