There is a large collection of documented demos available: Bitbucket (some of them are available as html: Demos — DOLFIN documentation).
As the current development version of dolfin, dolfin-x is the only version being worked on by core developers atm, there is a prototype tutorial based on the FEniCS tutorial available at: The FEniCS-X tutorial — FEniCS-X tutorial.
You can of course also use older versions of dolfin matching for instance the FEniCS tutorial using docker and the image quay.io/fenicsproject/stable:2016.2.0.r3