Two things to say:

First of all, Amazon will collect and remit all sales tax for you in California (and other states as well). You do not have to send any money to your state for Amazon sales. Other platforms generally do the same thing, but you are responsible for any direct sales made through your own website or store.

HOWEVER, you likely still have to file, even though you don't owe any taxes. I would suggest contacting your state tax office (possibly can find everything you need on their website); if that doesn't help, speak to a tax professional (not one of the just-out-of-school guys working at a pop-up tax store, but an experiences full time professional).