My fasta data are now integrated and available, If you encounter the problem, follow the wiki link : https://bitbucket.org/galaxy/galaxy-central/wiki/DataLibraries/UploadingFile...
I specify the location path of my data source in the universe_wsgi.ini file : as
library_import_dir = /my/data/location
and then import my data using the admin UI.
Thanks for your answer Jennifer, best regards, Ben