You can purchase a car either from a dealer and let they do all the paperwork for you. Yes you may pay more for the car but less chances to be scam.
If you go the route of purchasing thru a private seller, make sure the seller in willing to go with you to the CESCO (DMV) office to do the transaction. This way you are sure the car don't have any fines and the person selling it to you is the legal owner of the vehicle.
You do not need to have a PR driving license to own or register a vehicle.
You will be require to show ID (current license, passport, government issue ID).
You need to show proof of residence (water, electric, landlord contract, ect.)
This site may help;
Use Google to translate.