Below is the picture, it shows that the CD used 0 byte but it does have audio. Why is it like that? How to view real files and capacity of audio CD?
Audio CDs do not have a filesystem, that is why explorer will not show the tracks.
Instead you should install a music cd ripper, like CDex (http://sourceforge.net/projects/cdexos/) which can display the size of the audio tracks.
And what have you expected? :)
It will show zero free space because you can't write files to an audio CD. Similarly, you can't delete files from it, or move them to another location on the CD.
As an audio CD has a different format from a Data disk, you can't see in Windows Explorer its capacity: