Dear Ms. Barrillot,
Thank you for posting your request on History Hub!
We suggest that you search the United Nations Children’s Fund website https://data.unicef.org/crvs/senegal/ for information about how to obtain a marriage certificate for Thies, Senegal. The United Nations Children's Fund, originally known as the United Nations International Children's Emergency Fund (UNICEF), was created by the United Nations General Assembly on December 11, 1946 to provide emergency food and healthcare to children and mothers in countries that had been devastated by World War II. They collected data on the children & mothers assisted.
You also may find information about how to obtain Senegalese marriage certificates at Senegal Obtain Marriage Certificate.
We hope this is helpful. Best of luck with your research!