In Canada the Constitution consists of the Constitution Act of 1867 and the Constitution Act of 1982.
Start by consulting secondary sources (e.g, books, journal articles, encyclopedias). These sources contain broad overviews or explanations of the law and will direct you to specific primary sources (e.g, legislation, case law, etc.).
A treaty is a compact made between two or more independent nations. Treaties between the Dominion of Canada and First Nations peoples have been framed by the exchange of certain rights. Comprehensive Claims and Specific Claims are considered contemporary forms of treaties.