Wow, how impatient are you?! You allowed just 10 minutes for someone to answer before asking for "help" again...
Normally you would use "Bluetooth File Exchange" on the Mac to send files to the phone. However, according to the specifications of this phone, it's Bluetooth support is crippled to just 'object push for vCard only'. This means the phone will only accept Contact data via Bluetooth, not MP3 files.
So, you have to use the USB cable. A quick search came up with the following thread on the subject:
http://discussions.apple.com/thread.jspa?messageID=6464521