Cdiscount requires you to select the shipping methods that you support, with a minimum of selecting the "tracked" and "registered" shipping methods. Cdiscount offers all information about these shipping options in your seller central, we advise you to read through them to understand what the shipping methods actually mean. You can find this information by navigating to the following page in the Cdiscount Seller Central.
To understand what Cdiscount wants in terms of shipping, it's a good idea to read through the text in the red square.