Music Composer

Where can I get a music composer to well,compose music for doom?

You'll need a midi editor if you want to compose for original doom. However I suggest making mods (.it, .xm, .s3m, etc) with ModPlug Tracker, and using them in ZDoom or exporting them as midis, mp3s, etc. I find it a very easy editor and mods have a few advantages over midis also.

Uh, why not just make REAL songs with goosd synths and fake instruments or real instruments and use those mp3's?

Anyway, I would help you but I'm making music for my own game right now, and I don't really do continuous background style music, even for my mod it's dynamic music(ie kicks in at important moments).