N2S3 is a project hosted in SourceSup, a project management web platform for Higher Education and French Research organizations. You'll find the project in this link.
SourceSup provides free git repositories. If you would like to contribute with source code, you need to install Git in your local machine, create a SourceSup account, and proceed to clone n2s3:
git clone https://git.renater.fr/anonscm/git/n2s3/n2s3.git
If you want to contribute documentation, get in touch with us through the mailing list! (see the contact page)