On Android creating a new ringtone from any audio file is fairly straightforward but adding a notification tone is not. To add a custom tone do the following.
1. Create a “notifications” directory at the root of your sdcard. You can do this with Astro or by connecting your Android phone to your PC over USB. The directory should look like this.
2. Insert any audio file (wav, mp3, midi, etc.) in this directory and you will be able to use it as a notification tone.