When you look at the “Phone ringtone” settings on an Android phone you’ll notice that there is no direct option to use your own files, you can only choose from the predefined list set by the manufacturer (or the ROM builder if you have got a custom ROM). This is the same case with Notification tones and Alarm tones.
The easiest way to choose your own music file (MP3 etc) as a ringtone is to open it in the music player and then click on Menu and then select “Use as Ringtone”, but there is no similar option for Notification tones and Alarm tones.
If you have a few files then you can use an App like Ringdroid but then you have to do it one by one for each of the files. If you have a lots of music files then the way to go is to create folders called “ringtone”, “alarms” and “notifications” for each and then put the files you want there. Once you remount your sdcard or rescan it then you’ll see all your new music files ready to be selected as ringtones etc.