We've been asked a few times about using Audacity to create and edit audio files - but sadly I've no time to create training materials.
But wonderfully there is plenty of help out there on the Web. GuidesAndTutorials.com have a getting started guide for Windows users, while Steve Sloan at San José State University has created an Audacity getting started guide for Mac users.
If you've got something a bit more advanced to do have a look at the Tutorials section of the Audacity Wiki.
And let us know how useful you find these tutorials and if you think there is anything missing - if there is a demand for it, we'll try and develop our own.