#1. If your music is in iTunes (which it should be), just plug your new iPhone into iTunes, and it will copy everything onto it.
- or -
#2. If you have your music ONLY on your old iPhone (and not in iTunes), then you've got a problem it isn't supposed to work that way. In which case, you'll have to get a program like PodWorks ($8) to take all the music off your old iPhone, import it into iTunes, and then follow part one, like I mentioned above.