In iTunes help section of your computer you can search and find:
“Save a copy of a song in a new file format“
(1) Choose iTunes>Preferences, click General and click Import Settings
(2) In the Import Using pop-up menu, choose the format you want to convert songs to and click OK to save settings.
(3)Select one or more songs in your library and choose File>Create New version>Create [format} Version.
The songs will be saved in it’s original format and the newly converted song appears in your library.
You can choose either version to sync with your iPod.
“Save a copy of a song in a new file format“
(1) Choose iTunes>Preferences, click General and click Import Settings
(2) In the Import Using pop-up menu, choose the format you want to convert songs to and click OK to save settings.
(3)Select one or more songs in your library and choose File>Create New version>Create [format} Version.
The songs will be saved in it’s original format and the newly converted song appears in your library.
You can choose either version to sync with your iPod.