iPhone help

[LTRracer4]

Im trying to make some ringtones off my iTunes. Im following these directions:
http://www.ehow.com/how_2160460_custom-iphone-ringtones-free.html
At step 13 or 14 i am finding my files have no extension, so i cant change it to a ringtone file. Anyone been through this before, or know what i can do to solve the problem?

Thanks