Before starting, each user needs to open an account on the cloud: https://registration.lal.in2p3.fr/register. In addition, you would need Python 3.5+ installed on your computer.
Openstack is a cloud computing platform, containing many components that offer different services. Let's cite Nova for the compute, Cinder for the block storage, Keystone to manage identity, or Glance for image. All components can be found at https://en.wikipedia.org/wiki/OpenStack#Components. For our purpose, we need to install a few of them