You may have registered on eBaydotCOM. But don't worry about it.
Do you have your Canadian address on your account (and on your Paypal account)?
Do you have a credit card attached to your Paypal account?
You should be fine.
But.
Some, even many, US sellers will not ship to Canada or overseas. If you see an item you want, always click on the Shipping and Handling tab and confirm that the seller will deal with Canadians and how much he charges for shipping.