M3 M3T...Huh? Help Please

[NinjaKiss]

Hi I am new and was thinking of creating my own AMV. I have tried windows movie maker and it freezes my stsem or crashes it. So I took a look at your recommended programs and MovieXone came as highly recommended for newbies. So I downloaded it and now I am stumped. It seems the program only acknowledges M3 formated files. The problem is I have no idea what a M3 file is> I only have AVI, WMV formatted files. Are there any prgrams that would convert files to this M3 format? Thanks in advance for your help