What species is a Small translucent/ yellow spider?

I'd put my money on the common wandering hunter Cheiracanthium, often called the Yellow Sac Spider. Quite harmless, like almost all spiders, and nothing to get worked up over.

http://bugguide.net/node/view/3383/bgimage

This is most likely one of the garden orb weavers, or possibly a sac spider. until spiders get to near adult, they are very difficult to identify, even from photos.

In any event, your little friend will be quite harmless.

If it is inside, it would have a better chance to survive if you put it outside.

The only spider in California that may have a bad bite is the western black widow, and your little spider is not one of them.

Argiope aurantia, they are black, yellow, and fairly tiny.