translate English to French: Go to the "My MP3s" section, add the tracks of your choice to your playlists as you would do it with tracks from the Deezer catalogue. Be careful, you will be the only one able to play these tracks, your personal MP3s added to your playlist will not be available to the other Deezer members.
Pour cela, rendez-vous dans la rubrique "Mes MP3s", et ajoutez vos titres à vos playlists comme vous le feriez pour un titre du catalogue Deezer.