Hello from Chicago and welcome Discovery Educator Network Midwest Institute participants. I will be doing some podcasting from the institute as well as doing some brief - 30 minute - workshops on using Audacity to edit sound for movies and podcasts. Audacity is the application that I use to edit the "Speaking of History" podcast.
Here are some helpful links for getting started with Audacity:
Audacity - free software application which works with Mac or PC
Audacity Wiki Page - a ton of extra information on Audacity including a forum
Audacity Tutorial - one of many online tutorials on how to use the application for editing sound
Lame MP3 Encoder - a free program which allows you to create an MP3 file from a WAV file, can be added to Audacity as an add-on
River Past MP3 Converter - a free program which allows you to create an MP3 file from a Wav file or an MP3 file to a WAV file
Wesley Fryer Podcast Help Links Page - a great collection of links for anyone who wants to learn more about podcasting from the producer of the podcast "Moving at the Speed of Creativity"
These are just a few of the great resources available to edit sound files. If you have a resource you'd like to share please include a link in the comments below. Thanks.