Learn how projects are organized. What are applications and releases (releases is what we call 'distributions' in other ecosystems). Install rebar3, create a new release. Write a hello world inside this scaffolding. Learn how to run it, how to enter the shell. Learn what is OTP and gen_server. Write a simple gen_server app. Make it fall randomly each minute. Learn what is a supervisor, and how it can restart the failing app. Play with supervisor settings.

Write a highly parallel web scraper / downloader as your first project, with workers and supervisors, there are plenty of examples how to do this with Erlang.

Then, learn the rest of the language, now that you know its raison d'être.