i have a Samsung A711 (link below)

does anyone know how to change the message tone on it? i want to change to my own sound, not one thats already on the phone. thanks if you can help.

http://www.samsung.com/au/consumer/detail/support.do?group=mobilephone&type=mobilephone&subt ype=archive&model_cd=MUGA711ZKXSA&mode=C