Hi,first of all make sure the engine is cold,take off the rad cap and fill with water.Run the engine with the cap off until the top radiator hose is hot.The water level should now have dropped. Top up the rad with hot water and let run for a short while to let any air out of the system.Some peugeots have bleed screws on the hoses, if this is the case replace the rad cap and open each of these bleed screws (one at a time) starting with the lowest one.Make sure water and not air is coming out,as soon as this is the case then move on to the next bleed screw and repeat.JOB DONE..... Keep an eye on the water level for a few days, it may need topping up again.