Do I need to file sales tax when I sale on Amazon.com? I'm in California.?

Do I need to file sales tax when I sale on Amazon.com? I'm in California. My sales are very small, usually some used books, used computer software, about 10 transaction a month, total earnings over the past 6 month does not exceed USD3,200. If I have to pay sales taxes, when and how do I pay them? thanks for answering.