1.) Opening that URL will yield nothing. In any system or setup. Because you're trying to open a folder. Not a file.

2.) "Permission denied "- as Gianni said we can't know since we aren't on your server, we don't know with which account you're doing that etc etc etc.

BUT

3.) All this is academic since directly modifying the CENTRAL logo.png in the installed files instead of doing a custom skin is WRONG.

You're using this one thread to get answers on 50 different subjects and seem not to fully read or consider the inputs. Because I don't even need to read Gianni's blog post to know that he will never ever advocate changing the core files. And if he ever did he knows I would publicly rip him a new one.