When you play a song, the Now Playing screen appears:

Tap
, or press the center button on the iPhone headset (or the equivalent button on your Bluetooth headset).
Tap
, or press the center button on the iPhone headset (or the equivalent button on your Bluetooth headset).
Drag the volume slider or use the buttons on the side of iPhone. You can also use the volume buttons on the iPhone headset (iPhone 3GS only).
Tap
.
Tap
, or press the center button on the iPhone headset (or the equivalent button on your Bluetooth headset) twice quickly.
Tap
twice, or press the center button on the iPhone headset (or the equivalent button on your Bluetooth headset) three times quickly.
Touch and hold
or
. The longer you hold the control, the faster the song rewinds or fast-forwards. On the iPhone headset, press the center button (or the equivalent button on your Bluetooth headset) twice quickly and hold to fast forward, or three times quickly and hold to rewind.
Tap
, or swipe to the right over the album cover.
Tap Now Playing.
Tap the album cover when playing a song. (Lyrics appear if you’ve added them to the song using the song’s Info window in iTunes.)
You can display playback controls at any time when you’re listening to music and using another application—or even when iPhone is locked—by double-clicking the Home
button. See Home.
If you’re using an application, the playback controls appear on top of the application. After using the controls, you can close them or tap Music to go to the Now Playing screen. If iPhone is locked, the controls appear onscreen, then disappear automatically after you finish using them.