The info is about on a few other threads. From memory you need to plug your phone into your PC and mount the SD card.
Then create the following directories media/audio/notifications and media/audio/ringtones and put the MP3 files you want in.
The ringtones and notification tones will then show in the lists in settings. If they dont you need to reset your phone. Apparently it doesnt work for everyone and you might need to format your SD card. But it worked for me no problem.