Go to the GitHub link above, read the README, and pay special attention to the “CONTRIBUTING” section.
If you have questions and the README and CONTRIBUTING documents do not specify a way to communicate, then open Issues on GitHub with your questions. Try to avoid asking questions unless you’ve read everything and cannot figure out how to proceed: remember that everyone working on the project is volunteering their limited time, just like you, and try to be respectful of their time and energy.
I am unaffiliated with this project, this is just the general procedure for contributing to open source projects.