I purchased a song on the iTuns from my computer but the song didnt added to my library.
The song existent only on the iphone.
How I can add the song to my computer library too?
My particular field of expertise is iOS Jailbreaking and Unlocking.
If syncing it doesn't work, you'll probably have to manually extract the song and add it to your library by rooting your device using something like iExplorer or iFunBox. Make sure that your AppleID matches on both your computer and your iPhone.