Read “Études for Erlang”, by J. David Eisenberg, online for free.
Free Erlang Books
The first part(Programming) of the Erlang Reference book; “Concurrent Programming in Erlang 2nd Edition” is available for free in pdf format.
Reading “Learn You Some Erlang for Great Good!” should be one of your first steps in learning Erlang. Erlang is a functional programming language. It is a general-purpose concurrent, garbage-collected programming language and runtime system.