Sound Editing Progam

[Pinkie Pie ☆]

Most people have already suggested this but I would also recommend that you use Audacity. It's open source software so it's free to use as you wish and it's pretty easy to use.
I like it because it's great for layering tracks and then you can just export it was an MP3 or WAV file.

The tools on Audacity are really easy to use aswell as they are all in one menu instead of having to look all over the place for little icons and stuff.
It's great for trimming, modifying and creating mixes of songs.

[m4dh4ck3r]

I prefer Audacity cause its Free,Easy to use,Occupies less space and doesn't use much CPU or RAM .

[DaMcmasonmc]

I use audacity. After spending a few months working with it occasionally its hard to use anything else. Learning audacity is annoying though as you keep getting grayed out buttons if playing or paused.

[Pikachu]

Audacity is a decent program, I can edit music so I can add them to a youtube video without getting copyrighted.