1. From the Idle screen, press Menu ➔ Settings ➔ Personalize ➔ Phone settings.
2. Choose USB mode ➔ Media Transfer Only.
Once you connect your phone to a computer using a USB cable, this will allow your device to be detected an as external storage device and enabled for data transfer of files between your phone an a communicating computer
Your phone will appear as a removable drive in My Computer, in which you can now drag your ringtones, pictures and other files.