How to sync more than 1 music to my Ipod Shuffle on Itunes?

How to sync more than 1 music on my Ipod Shuffle on Itunes? my ipod only sync 1 music, i dont know how to sync more musics, when i listen to my ipod i hear only 1 music. i sync more than 1 music but when i check(listen) my ipod shuffle only appear 1 song, why? can you help me? thanks