1) Obtain and install Debian GNU/Hurd;
2) Subscribe to the Debian GNU/Hurd mailing-list: Send an E-mail to firstname.lastname@example.org with subscribe as the Subject;
3) Use Debian GNU/Hurd, install new packages, and send comments to the mailing list, and bug-reports to email@example.com
4) If you have the knowledge and skills, offer to help in its development - new volunteers are needed and welcome;
5) Inform others about GNU/Hurd and get them to install it.