To become (or keep) Superhost, you need to have an account in good standing, and over the past year*** (I assume past year means counting back from current day).
- Hosted at least 10 trips
- Maintained a 90% response rate or higher
- Received a 5-star review at least 80% of the time you’ve been reviewed, as long as at least half of the guests who stayed with you left a review
- Completed each of your confirmed reservations without canceling
You can track your progress in the Superhost section of your dashboard.
btw: The HELP section on your dashboard is a good source for articles. Less chaotic than searching the forum if all you are looking for is Airbnb terms, conditions and policy.