you will need to find out why you have lost your gearbox oil, if leak found you will need this fixed or you will lose more oil. if you ask at a renault dealer they should be able to tell you where filler is, once you have put right type/amount of transmisson fluid in you will need to strat the car, and keeping the brakes on, go though the gears to settle fluid thoughout the gearbox. if you still have trouble with box then you might need to go to an auto transmisson techie.
hope it helps, September 2010