If you want to teach French at a French-language school, you will need an undergraduate degree from a university or college, e.g., a BSc. or BA, and then you will need to complete a Bachelor of Education (BEd) degree which qualifies you to teach at a K-12 school.
French-language teacher education (BEd) is offered at two universities in Ontario: Laurentian University in Sudbury and the University of Ottawa, which also offers programs in Toronto and Windsor.
Apply to a teacher education program through the Ontario Universities’ Application Centre. It is a non-profit centralized service for students applying to Ontario faculties of education.
If you are already a qualified French-language teacher, you can find jobs through the Jobs in Education website.