The easiest way to search for legislative history, for the legislation passed beginning in 1993, is to use the Legislative Counsel of California's Bill Information website. The bill information at this site includes the full text of bills, resolutions, and constitutional amendments and their status, history, votes, and analyses. Veto messages can also be found on this site.
There are two versions of the California Legislation Information website. They are both official, but they cover different time periods. The current one covers the 1999-2000 legislative session through the present day.
The earlier one overlaps considerably with the current one. The coverage runs from the 1993-1994 legislative session through 2015-2016.
The Law Library has similar resources in-house for this time period, as it has for the pre-1993 period.