Touch a song in your library to listen to it.
OR
While viewing a list of tracks in an album, touch the Menu Key > Play all
.
The Playback screen opens and the song you touched or the first song in the album or other playlist starts to play. Your music continues to play even when you switch applications or receive a phone call. The tracks in the current playlist play in order until it reaches the end, then stops. If you choose a repeat option, playback only stops when you stop it.
You can return to the Playback screen from most other screens in the Music Player application by touching the currently playing song at the bottom of the screen.
You can return to the Playback screen from any other application by opening the Notifications panel and touching the ongoing music notification.