Clarify your status in Canada?
If you are a Landed Immigrant or Citizen, you would have to prove you are in danger remaining in Canada. Good luck! (hard to do!)
If Canada has rejected your application for refugee status, most likely the US will, too.
If you are passing through Canada, no permanent status in Canada except as a visitor, you might be able to do this - if you can prove you are in danger in your home country.
You should have travel documents....(!)
More info is really needed to better answer your questions...