Radio installation VW Fox – HELP –

Hello, I have been a lucky owner of a VW Fox in silver-metallic for a few days. However, the good part has no factory-side radio and only a preparation in it (is an EU import from France). I have now got a Sony CDX-GT200 and a car radio adapter “Autoradio ISO auf VW” (from aiv) from the local Saturn (I don’t need radio). Now I have read the corresponding posts from the forum, but without success: I have the adapter to the cabling g connected by the Fox and to the adapter again the radio. Result: the CD Mechanics worked, but not everything else. Wants to mean that he leads CDs into the shaft and spits out again. More but not more. I have often read that I have to connect a cable of the adapter to the fuse. However, I did not have a plan like that worked. Maybe it would be possible that someone would put me a SChritt for step instruction here. Would be nice, would nämli ch likes to listen to music in my beautiful new car. Another question. What are the openings next to the exterior mirror adjustment? Are the vents or are the tweeters? Thanks already in advance.