You need to decide if you're going to hibernate him or not. If you don't, then he'll need a proper enclosure inside with heat/light and a good UVB source. If you hibernate him, you might want to consider the fridge method (don't know how warm it gets in California in the winter, but it might be too warm). Here's a link to a good guide to hibernation:
http://www.thetortoisehouse.com/
(just click on the hibernation section)
And here's another link re the pros and cons of hibernation and more:
http://www.turtlestuff.com/hibernation.html

Nina