- Seller writes car of his name and gives you the original old registration paper.

- You call an insurance, arrange your insurance on the phone and ask them to send a signal right away to STVA that the car is insured. (or do it all by paper if you are in no hurry)

- You can now go to STVA while bringing along your ID and the old registration.

- STVA will fix registration within minutes and hand you your new plates at the same moment.

- Put on plates and enjoy your new car.

Tip: Know the size of the numberplates you need so they can give you correct ones.

EDIT: Oh wait it is a new car, at least step 1 is different in your case. Talk to your dealer so you know who does what.