How to transfer all my music from windows media player to itunes ?

Hi checker32,

Importing audio files into your iTunes library can be done using the steps listed in this article -

iTunes 11 for Windows: Import music and video already on your computer

http://support.apple.com/kb/PH12493

Note -

If the file is an unprotected WMA file and you have Windows Media Player Series 9 or later installed, iTunes makes a copy of the file and adds it to your iTunes library. The original WMA file remains unchanged. You can’t add protected WMA files or protected WMV files to iTunes.

Thanks for using Apple Support Communities.

Best,

Brett L

You may find this user tip useful:

Getting iTunes & Windows Media Player to play nicely

tt2