To begin your search you will need to know the name of the birth mother and the year of birth. Already you can see that this may be complicated. I found a great article on adoption research by Maureen Taylor. Use this link to access the article, http://www.genealogy.com/69_taylor.html.
Every country has a set of adoption laws. In searching for your birth family, by Ontario law, you are entitled to receive from the Government of Ontario the Adoption order, all non-identifying information regarding yourself and maybe, a certificate of "live birth", Click here. Other provinces have different adoption disclosure laws. You will have to check with that province.
Here are a few helpful sites:
Parent Finders of Canada & Parent Finders Ottawa-click here
Finding your Birth Parents in Canada- click here