I think you have to show up in the courtroom to get your ticket reduced... if YOU live in CA that might not be feasible, so your only option may be to send in a check for the fine.
You may be able to contact the courthouse in the county it was issued and talk to the Clerk of the District Court for more information. If you can go to that courthouse, go to that dept and show them the ticket and ask your questions.
Sometimes on the bottom of the ticket in fine print, there may be an additional fee for paying by check... My BFF didn't see that and had her license revoked due to sending in a check but not including that amount too :roll:
Also during this time of the year, it is a good idea to send it so they have to sign for it... mail gets lost easily with the volume moving around between now and Christmas.