Install Node.js from http://nodejs.org/
Create a folder for your project
mkdir weather
cd weather
Install require modules
# Install CoffeeScript globally so that binaries are installed
sudo npm install -g coffee-script
# Install openweathermap module locally to the project folder
npm install openweathermap
Create a file called weather.coffee
weather = require 'openweathermap'
weather.defaults
units: 'imperial'
weather.now q: 'Chicago', (data) ->
console.log data
Run it
coffee weather.coffee