'02 Puegeot 206CC Power steering noises,?

My 2002 Peugeot 206cc has developed grating noises when I turn the steering wheel with the engine running. I'm guessing its a power steering problem. If so what fliud should I get and How do I find the filler cap, if it needs topping uip, (there are a number of fillers and I dont want to use the wrong 1).
Could the problem be more serious?
Thanks