Here is the basic info on the edits challenge when it was annouced in the forums:
Info abut how to submit edits via the games is available in the help section of the Wayfarer website, as well as the Wayfarer help center, under How can I access Niantic Wayfarer? Here are the direct links for submitting edits via Ingress and PoGo:
Lastly, being you’re French, please know that you aren’t required to type in English in the forums, as we do have a translator. If you feel more comfortable with French, you can type in that language, as well as view the forums in it. This setting is under Preferences > Interface > Interface Language.