Going by the name of the demo you are trying to run: Clamped semi-cylindrical Naghdi shell under point load — fenics-shells
You should consider
https://fenics-shells.github.io/fenicsx-shells/
For general FEniCSx demos see:
https://docs.fenicsproject.org/dolfinx/v0.8.0/python/demos.html
Or
https://jsdokken.com/dolfinx-tutorial/