How does iphone4s change short messages into ringtones?

Open itunes and click (Edit)-(Preferences)-Check (Ringtone) in the upper left corner.

Library-Music Click (File) in the upper left corner to add a file to the library (select the music you downloaded from your computer).

After selection, add music with the right mouse button. Click on the music file (exhibition introduction) and click on the (options) tick (start time) and (stop time). I set the music time to 39 seconds.

I don't know how long it can be set ~ and then click (OK)

Right-click the music file (create AAC version). At this time, you find that there is a file below with the name of the ringtone you chose, which is an ACC version created by right clicking for a short time.

This file selection (displayed in windows Explorer)

The file name that appears is: (May-my dearest m4a)-changed to-(May-my dearest.m4R).

Go back to itunes and double-click (May-my dearest .m4r) from Database-Music, and you will find it in the ringtone.

Then select the left side of itunes (device), click your iphone4s name, click (ringtone) in itunes (under Apple logo) to synchronize ringtones (it's up to you to decide all ringtones or choose ringtones), and ringtones will be ready.

Turn on the phone (settings) (voice) (phone ringing), your (May-my dearest .m4r) is already on Malimba.