The Superior Drummer 3 manual can be accessed at this link: https://www.toontrack.com/manual/superior-drummer-3/
Please note: you must be logged into your Toontrack.com account in order to access this link. If you are not logged in, clicking on this link will first prompt you to login, then you will be able to view the manual.
The manual can also be accessed from the Help menu in the Superior Drummer 3 software.