The best option is to contact prospective supervisors as the scholarships available and rules that apply will depend on the province, university, discipline etc. There are situations where you will receive monthly pay during the PhD from your supervisor as a Research Assistantship, or the University as a Graduate Teaching Assistantship. Generally, the less funding available from supervisors and scholarships, the more Graduate Teaching Assistantships you need to do. In Ontario, there is a competitive scholarship called 'Ontario Trillium Award' for international students. But you need to have a supervisor in mind who will suggest you as a candidate, which is often the case for scholarships at the PhD level. A big funding body for science in Canada is NSERC (equivalent to NERC in the UK). There are scholarships available for internationals, but they are very competitive/very few.
I suggest you think about what it is you want to study and contact professors who have a similar focus. Also keep looking online for funded PhD's on specific topics. If you find one, contact the Principle Investigator to find out your options.