For the building blocks of an SSI application, see the Jolocom SDK and it's documentation.
For a similar example application, see the Interactions Demo (in particular the service_agent subproject)
Documentation for the generic backend is currently hosted here.
The backend should work with node v10+
Make sure you have redis installed. Find installation instructions here: https://gist.github.com/tomysmile/1b8a321e7c58499ef9f9441b2faa0aa8