Make a folder on you sdcard or if one is already there called Media then inside that one add a folder named Audio then inside that Ringtones <--add ringtones here. Reboot phone and you should see them listed when you change your ringtone.
Try using Root Explorer/ES File Explorer and move them to the following folder...
/system/media/audio/ringtones/
Just make sure you have write permissions enabled so you can copy and paste to /system/ level folders of the device.