Feel free to open an issue for bigger effort changes and ask if you can help or get help with your idea. For typos and documentation improvements just make a pull request.
Then:
- fork the repository on GitHub
- code and add tests that cover the created code. Your code should be warning-free.
- stick to PSR-2 and and don't reformat existing code.
- make a pull request. @jenschude will review it and pull or come back to you.