voici la réponse ! c est en anglais mais tu devrai pouvoir te débrouiller
How to Install a CnC: Generals Map:
Extract the contents of the zip / rar / ace archive to your My
Documents folder then in that folder to "Command and Conquer
Generals Data/Maps/" and you´re all set! Make sure that within
the Maps folder the . map and . tga file ( and possible others) are
in its own directory carrying the name of the map!