It's one thing to listen to music, and it's another to create it, edit it, or mix it. If you're interested in creating, editing, and mixing you'll want Audacity. This powerful, free, Open Source tool can record sound and music as well as edit it, so you'll want to start off recording your audio. After that, you edit, and it offers a surprisingly powerful set of tools. In all likelihood, it's got more horsepower than you really need. It lets you add several dozen sound effects, has a powerful mixer, and much more. It works with files in the.MP3, .WAV. AIFF, and Ogg Vorbis file formats.
What can you do with Audacity? You can cut and paste sections of a recording, or delete entire sections. You can use fades and other effects, and mix an unlimited number of tracks. You'll even be able to create your own "soundscapes" by generating sounds and mixing them. Audacity is good enough for engineers, and for those who just want to play around with sound as well.