I am confused. You say OverDrive change the format from WMA to mp3. But then you ask how to do that?
Do what since you said OverDrive did that?
The iPod can't play WMA files. They have to be converted to a format compatible with the iPod.
Itunes Help includes:
Do either of the following:
- Drag a file or folder from the desktop to the iTunes window.If you add a folder, all the files it contains are added to your library.
- In iTunes, choose File > Add to Library, locate a file or folder, and click Open.
By default, adding items to your iTunes library places a pointer to each file in the iTunes folder; the original file remains in the current location. For information about copying files to the iTunes folder instead of creating pointers to them, see Change where your iTunes files are stored. 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.
You can also get computer apps to do the conversion