The main repository for Idyll is here: https://github.com/idyll-lang/idyll. Feel free to open issues or create pull requests.
There is also a public chatroom on Gitter if you'd like to say "Hi!" or ask a quick question.
Contributions are welcome! If you want to start working on anything in particular, it's a good idea to post in the chatroom, or a post comment or an issue on GitHub so that multiple people aren't trying to fix the same thing. Feel free to reach out to me on twitter or via email, idyll at mathisonian dot com.