To fix a car, first identify the problem by checking the engine, brakes, or tires. Look for warning lights on the dashboard and listen for unusual sounds. Gather necessary tools like a wrench, screwdriver, and jack to assist in repairs. Next, consult the owner's manual for specific instructions related to your car model. If you need to replace parts, ensure you have the correct replacement parts. After making repairs, test the car to ensure everything is functioning properly before driving it again.