Creating a club with the right visibility for how open you want it to be, joining one that's already running, and what changes once you're an owner or moderator.
Clubs > Start a Club asks for a name, an optional focus make if the club is built around one manufacturer, a description, and who can join. You become the club's owner the moment it's created.
Public clubs let anyone join instantly. Private clubs let anyone request to join, but an owner or moderator has to approve the request first. Invite only clubs have no self-join option at all, membership is by invitation, sent to a specific handle, only.
The join button on a club's page adapts to its visibility automatically: Join Club for a public one, Request to Join for a private one, or nothing at all for invite only, where you'll instead see an Accept or Decline prompt if you've actually been invited.
Owners and moderators get a management panel with tabs for pending join requests, sending invites, and the member list. Only the owner can promote a member to moderator or demote them back, and either an owner or a moderator can remove an ordinary member, though not each other. An owner can't leave their own club without transferring ownership first.
If you own or moderate a club, Events > Create shows an extra Official Club Event dropdown. Attaching an event to your club adds an "Organised by" badge to it and lists it in that club's own Club Events section, rather than it just being an event you happen to have organised personally.