We still need to define a process...
But initially get in touch and discuss what you want to contribute. We have [[https://developer.emblem.net.au/Z8|a chat]] that we might be found on. You will need to sign up to our Phabricator which currently requires approval. When you sign up one of us will email you to verify you're not a bot and to find out what you want to do. This might be a bit cumbersome or controlling but we are still trying to figure out how we want to host out project management since this Phabricator is home to other internal projects as well. In the mean time we plan to just talk with anyone interested.