Assumes you want to use Stylus as your css preprocessor
You will need yeoman
npm install yeoman -g
npm install generator-gaffa -g
Create a new folder for your app
mkdir yourApp
cd yourApp
yo gaffa
This will install Gaffa.js and dependencies. It will also present some command-line options for setting up your app.
You will develop your application in the /app/ folder. To preview in a webpage run:
grunt server
This will present a browserified app using grunt-browserfiy which watches the following two files for changes:
app/scripts/app.js
app/styles/styles.styl
Develop your app by modifying these two files.