A majority of car dealerships take the hassle of registration out of your hands and they will complete the CA registration for you. The only thing you need to do is pay the registration fee at time of purchase, then sit and wait to receive your permanent registration certificate and the registration sticker in the mail. This fee is limited to, at most, $120 for all CA dealers. It is a win/win for both parties because it lessens the risk for the dealer and increases the ease of transaction and satisfaction for the customer.
The dealership should provide you with a temporary operating plate (TOP) which is valid for 6 months or until your registration is done processing, whichever date comes first. If you do not come across a dealership that will not process your registration for you, you will need to register your vehicle in person within 10 days of purchase.