You can't. You would have to find an employer who is able to get a Labour Market Opinion from Service Canada "that there are no Canadians or Permanent residents available for the job, and the wages are the local norm" Once you have the LMO then you apply at an office outside Canada for a work permit, you have to demonstrate that you have the skills for the position, and you may require a medical. Only then will you be issued a work permit to allow you to work in Canada. Start your reading at http://www.cic.gc.ca/english/work/index.asp
