step1:first u have to download a file manager system for your android phone from google play or from any other sites ,i prefer to use astro file manager system.u can use any other one as u like
step2:install file manager app and open go to music directory folder or where your music is available to set for phone ringtone (choose music file to set ringtone as u like),and copy this file.
step3:now go to sd card 0 directory and locate ringtone folder
sdcard0>ringtone
step4:paste the music file which u copied from step2 into ringtone folder now exit and open setting menu from main menu click on sound setting than phone ringtone list your music file is available for ringtone
