If you make the group public, anyone will be able to view your group, and public games that are posted in the group become visible on the OpenSports public events page.
If the group is private (invite-only), the group administrator(s) must invite players to the group, and group does not display on the OpenSports groups page. Games posted within private groups will show up on the OpenSports games feed if they are public games. Private groups are invite-only and are invisible to non-members.
You can change your group from a Public to a Private group (And vice-versa) through the Edit button.