Do I need to be a dealer to sell my car

No you do not. You can get a state approved Bill of Sale and Title / Registration Application form typically online at your states DMV website, but all you really need is a Bill of Sale which you can actually hand write. Critical info to include on your bill-of-sale is Date sold, VIN #, Year, Make, Model, Mileage, Sellers Name and Address, Buyer's name and address, selling price, and be sure to include "VEHICLE IS SOLD "AS-IS" with NO WARRANTY WRITTEN OR IMPLIED" to protect yourself and a place for the buyer to Print and sign thier name. Be sure to make TWO copies, one for you and one for the Buyer.