Never too late!
Welcome on board, Pietro! The way to register is by ticking the box in your user profile.
You’re just in time to propose a session, do you know how to? simply upload a post in the Making Lote3 group, containing the details of the session - is it a workshop, a talk? how much time you need? requirements for participating in it, if any etc (example here) - and tag it under the activity track you think is most suited: Track 1 is Upskilling for Change (we teach each other stuff to get better at realising projects), Track 2 is Building the unMonastery, and Track 3 is the unConference. Let me know if you need help!