First and foremost is to buy a car then :
To register your car for the first time in the State of Florida, the process is pretty simple: Just bring the original title, proof of required insurance, and all applicable fees to your nearest county tax collector's office or license plate agency. If you're renewing registration, bring your renewal notice in place of the original title.You can also renew your vehicle registration online or by calling 1-866-467-3639 (GO-RENEW).

Vehicle registration is valid for one year, a period which usually begins in the vehicle owner's birth month. (Fleet vehicles owned by a company all use the month of June.) Even if you register your car late, you'll still be required to pay the full registration fee as follows:

* Automobiles, private use (2,499 pounds or less): $27.60

* Automobiles, private use (2,500 to 3,499 pounds): $35.60

* Automobiles, private use (3,500 or more pounds): $45.60

* Trucks, private and commercial (1,900 pounds or less): $27.60

* Trucks, private and commercial (2,000 to 3,000 pounds): $35.60

* Trucks, private and commercial (3,001 to 5,000 pounds): $45.60

* Transfer of a license plate from another vehicle: $4.60

* Issue of a new metal license plate: $10

* Initial registration fee: $100
Full details on this site:
http://www.dmv.org/fl-florida/car-registration.php