how do I replace the right front signal light. Do I have to replace the whole assembly or can I just replace the lens?
On most cars you simply replace only the bulb, usually by reaching behind assembly. You may be able to reach it by opening the hood and coming in from the top, else by reaching up from underneath. Grasp the socket and give a slight counterclockwise twist.
Are you asking about replacing the assembly because the plastic lens is broken?
yes the plastic lens is broken