Itunes does not identify old music contents on new computer -

Question

I have moved "my music" contents from and old computer to a new one. Itunes does not recognize these contents.
How do I make them corelate?

Answer 1

If you use automatic syncing, you must set up the iPod's Music tab in iTunes so that the selection of songs includes all the songs you want on the iPod.
Select the iPod in iTunes.  There is a row of "tabs" (starting with Summary).  Click on Music there.  That is the Music tab, where you tell iTunes how to sync songs to the iPod.
To use automatic syncing for songs, Sync Music is checkmarked.  You can choose to sync Entire music library, if it fits.  Otherwise, you can choose to sync Selected playlists, artists, albums, and genres.
If you chose the latter, you create a selection of songs on the Music tab by selecting playlists, artists, albums, and/or genres.  For example, if you want that new playlist, it must be checkmarked under Playlists.  If you want to keep it simple, you can create a new playlist in iTunes and put ALL song you want on the iPod on that playlist (including that new purchased song).  Back on the Music tab, checkmark that one playlist.
When you Apply the change, your selection of songs on the Music tab syncs to the iPod.  If the iPod was not previously set to use automatic syncing, its existing content is replaced.  Going forward, any changes to the iTunes Music library that relate to the selection of songs on the Music tab sync automatically when the iPod is connected, or when you click Sync.  So, if you are syncing a playlist as your selection of songs, just update that playlist (add and remove songs), and the iPod gets updated with those changes at the next opportunity.