Audacity is a free audio editor that can be used on Windows, Macintosh, and Linux operating systems. By itself, Audacity can record, edit and save uncompressed audio files, as well as add special effects. You can also convert sound files to MP3 format for use on web pages, to create podcasts, or to play on an MP3 player such as an iPod. You will need to download an additional file to perform the MP3 export, but it is easily installed on your computer. You can find further information about using Audacity on their wiki page (support site).
You can view a screencast (about 7 1/2 minutes) that will show you how to install and set up Audacity and install the MP3 export feature. You can also view a PDF document on how to install Audacity (PC and Mac) and how to record and save an audio file to MP3 format.
For more information, see all of our Digital Audio articles that will give you background information on audio players, audio recording, editing and more.