How to add ringtones to an iPhone?

I have a Chinese coworker that would like me to put some Chinese music on her phone that she can use as a ringtone (specifically the theme to shanghai tang) I'm an android user and I've tried everything that would have worked on my phone, but they don't work on hers. I have the files on my phone in mp3 format, it won't let me download directly or transfer it by Bluetooth. This woman can barely speak English, and does not know her apple id or password. I would really like to help her

I heard the nexus 4 is much better.