@The Running Man, a short answer is to check out the CA BPELSG website, here:
https://www.bpelsg.ca.gov/applicants/appintrope.shtml
That has links to pretty much all of the information you need to fill out the application for licensure as a California Civil PE.
Long story short, you need to fill out the application (and do all the things in the checklist for a complete application) and have it be approved by the CA BPELSG before you will be able to register to take the state-specific seismic and surveying exams. When you pass these exams, you will be a licensed CA PE!
Bear in mind, the quarter status for the state specific exams is worth paying attention to. There are some good posts earlier on this page talking about rationale regarding when to schedule the exams within a quarter.
Also, note that the application can take some time to put together (seeing how it needs reference forms) and the ethics exam isn't hard, but does take some dedicated time. Then the review period seems to take at least 2-3 months, based on people's anecdotal experience on this board.