Trying unsuccessfully to make iPhone ringtones?

I used an MP3 file and clicked "show in Windows Explorer" and changed the mp3 to m4r. ITunes won't play or add the ringtone. I'm using the newest version of iTunes. How can I get this to work?

You forgot the part where you have to go into iTunes and right click the song to create an Apple lossless version (m4a) which is then changed to m4r.

Look over the instructions
http://www.iclarified.com/entry/index.php?enid=439