Welcome. There's nothing you "do" in a mailing list, per se. If you have questions or issues, you can raise them here, and you can participate in discussions that arise by using Reply All.
Stay in the mailing list for a little while; contribute to discussions knowledgeably (read the Archwiki); adopt more packages from the Orphans section of the AUR; contribute to Archlinux projects (https://gitlab.archlinux.org/archlinux); join the IRC channels and be active. Becoming a Package Maintainer takes time and trust. These are ways you can start gaining the latter. Sam
