If you have a Main module, you can run the compiled js file with node automatically.

node elm.js

You can also import the file as a library, setup any ports, and start the program manually.

var Elm = require('./elm.js');

Elm.worker(Elm.Main, {});

The API is still very experimental.

module Main where

import Task exposing (Task,andThen,onError)
import Console
import File

port main : Task x ()
port main =
    File.read "elm-stuff/exact-dependencies.json"
        `andThen` Console.log
        `onError` Console.fatal

For a more in depth example, checkout elm-oracle.