It is difficult to change from AR to Ecto, it’s quite different.
But You might find a good free resource here
http://pages.plataformatec.com.br/ebook-whats-new-in-ecto-2-0
And this new book on Ecto
Ecto is closer to sql… here is a simple query
q = from m in Meeting, where: m.user_id == ^current_user.id
Repo.all(q)