1. in itunes music library, right click on the song you want to make a ringtone
2. click get info & go to options tab
3. set the start & stop time to not more than 30 seconds. example, if you want the 1st 30 secs of the song for your ringtone, set start to 0 & stop to 30. you can do this to any part of the song just remember the start & stop time. when you're done, click ok
4. right click on the song again & select convert to AAC
5. you'll notice that in your music library there are 2 songs with the same name but different duration. set the original's start & stop time back to original by unchecking the start & stop option.
6. now, right click on the other song (the shorter duration one) & select show in windows explorer.
7. a new window will open. rename the extension of the song from .m4a to . m4r
8. double click the song & it will automatically appear in the ringtone panel of itunes.
9. just sync your iphone & enjoy your new ringtone

A while back I found this online editor [Only registered and activated users can see links]
It supports .m4r format.

i tried creating a ring tone wen i sncy from itune a msg appers tat a file cannot b found can any 1 help??or tyell me what is the problem

did you move the ringtone to other locations before syncing? did you rename the file to .m4r? try again & follow my instructions..its easy really =)