Free Music Editing Software

http://mp3.about.com/od/essentialsoftware/tp/bestaudioeditors.htm

http://www.hongkiat.com/blog/25-free-digital-audio-editors/

Free music editors, personally, I find that Audacity works wonderfully.

As far as free music *makers* go, I'd personally recommend Deckadance and FL Studio

I'd advise, if you get really confused to go with Sony Acid and try it out.