How to add Ringtones to an iPhone
a) Connect your iPhone to your computer.
(Windows or Mac with iTunes on it) Use an USB cableand connect your iPhone with your computer.
b) In the meun bar of iTunes click on File and select Add to Libary.
c) In the Add to Libery section find your M4R file which you have uploaded to your computer.
d) When you found your M4R file in the Add to libery section click Choose.
e) click on Ringtone in the sidebar of iTunes.
f) Drag and drop your M4R file from the libery window to the iPhone icon in the sidebar.
ITunes transfers your ringtone to your iPhone.