Contribute via GitHub.

Submitting bug fixes and enhancements is easy:

    1. Log in to GitHub

    2. Fork the Monstra Repository
        https://github.com/Awilum/monstra-cms
        Click "Fork" and you'll have your very own copy of the Monstra source code at http://github.com/{your-username}/monstra-cms

    3. Edit files within your fork. This can be done directly on GitHub.com at http://github.com/{your-username}/monstra-cms

    4. Submit a Pull Request (tell Monstra about your changes)
        Click "Pull Prequest"
        Enter a Message that will go with your commit to be reviewed by core committers
        Click "Send Pull Request"

Links:
Monstra on GitHub
Got 15 minutes and want to learn Git ?
git - the simple guide