How to get to the serial of Renault Help!

Hi All,
I recently changed the battery on Renault Megane II (car was bought used), and although I got a sticker on some renault bag that contains a code, it doesnt work for some reason. Now I have no idea how to get to the radio serial you guys need to help me get the code. I have a Carminat (Convertible stereo?) inside with two "slot" holes which are probably used to extract it but i dont know in what way. Any Ideas?

Thanks Alot for help!!!