You may be able to locate ceremonies in Canada by searching in Meetup.com groups, Facebook groups or other social media groups that deal with Ayahuasca. You really need to understand that Ayahuasca is illegal in Canada and taking the medicine is an act of civil disobedience.
If you’re fortunate enough to find a qualified shaman in Canada who is conducting ceremonies, use some discretion and follow his or her instructions accordingly. However, based on news reports, the authorities don’t seem to be actively prosecuting at this time. This could change at any time but the Ayahuasca Defense Fund offers compelling reasons as to why authorities should not be prosecuting people who take or administer the medicine.
Without getting too deeply into the reasons for the illegality of the medicine, Graham Hancock offers a compelling insight on his banned Ted Talk on YouTube.