File has to be in default music storage directory before it can be recognized as a ringtone - unless you download an app like ES File Explorer. If so, when you go into settings in the phone app to change ring tone, you will be prompted if you want to use Music Storage or your file manager to complete the action. Choose the file manager but "only once" option. Browse to the file and select it. After this, the file will appear in your list of available ring tones when you bring it up from phone app settings.