You need to purchase transmitter and receiver on the same frequency, a steering servo batteries and an esc (electronic speed control). Design a way to mount the steering servo to the steering system, mount the receiver, antenna and esc inside the car with the antenna sticking up, connect the esc. to the motor. Charge the batteries and away you go. It will be much cheaper to just buy a premade r/c car but you won't learn anything about building r/c cars and building it is more than half the fun. Good luck.