I missed something (audio convert to MP4/aac)

[Dude]

I recently downloaded mediacoder and I foolishly skipped over some stuff that would have helped me understand what the heck Im doing. All I really want is to change the format on some music files to mp4 rather than mp3 so I can play on a DSi. Being rather technically challenged and since theres no helpful button that says "Press Here to Change Format" I have no idea what Im doing,. If anyone can just give me a push in the right direction I would be rather greatful.

[Dude]

Alrighty, well you've given me alot to stew over. and to answer:

1. Im trying to go from mp3/wmp format to mp4
and
2. I dont believe that it needs a video signal.

Also can Mediacoder convert the files or do I have to go elsewhere on the internet?