How do I go about finding internships in French speaking countries?

There are a number of ways to find international internships. From experience of friends of mine a good starting point is to go to https://aiesec.org/, an organization which helps finding international internships. Also looking through your linkedin to see if you have 1 or 2nd degree contact in a French speaking country and contacting that person to see if he/she is open for discussion potential internship opportunities. Hope that helps as a starting point.