Because voting is a right, I believe all those qualified should be registered automatically, leaving only those wishing to unregister acting to affirm their choice of abstention. Regrettably, our current system requires those qualified taking proactive steps in registering to affirm suffrage. This system is what it is (right now), and so we must work within it.
Considering most states, voting in California is comparatively easy. As noted, you must first be a registered voter. You may register online, and it is rather quick to do. You may also choose permanent absentee voting, which means you will receive your ballots via the mail, rather than showing up at polling places. If you prefer showing up, there is plenty of time for voting early, so none need wait until Election Day itself.
If you previously registered, it may help to check your current registration status to ensure your voting address matches your current address. For local elections, which includes the District 6 election, San Francisco offers "ranked choice" ballots. This means you may select your preferred candidates, ranked one through three. Your most preferred choice is first, followed by someone you could settle for, then a third suitable option, if having one.
I strongly suggest watching the video below, which best explains "ranked choice" voting.
Though any person may support my candidacy as a volunteer, donor, moral supporter, and so on, only residents of District 6 will see my name on their ballot. I suggest viewing the District 6 page to help discern if you may be a constituent of the district.
If not a constituent, remember many decisions of our Board of Supervisors impact the whole City. I hope to earn your support, regardless of where you live. For those in the district, while I hope to earn first place on your ballot, I will nevertheless be privileged to earn any place on your ballot.