This video is a good place to start: Twitter in Plain English. It was created by the folks at http://twitter.com/#!/CommonCraft You can follow them on Twitter to learn more.
Try these links for some additional tips.
http://technmarketing.com/2009/03/top-5-reasons-to-tweet/ Top 5 Reasons to Tweet
http://technmarketing.com/2009/03/first-5-steps-after-joining-twitter/ First 5 Steps After Joining Twitter
http://technmarketing.com/2009/04/ten-things-you-must-know-before-using-twitter/ Ten Things You Must Know Before Using Twitter
http://technmarketing.com/2009/05/top-6-ways-to-benefit-from-twitter/ Top 6 Ways to Benefit from Twitter
http://technmarketing.com/2009/07/9-advanced-twitter-tips/ Nine Advanced Twitter Tips
We'll also post more info from the class. Take time to read these articles. They're chock full of simple, good-to-know information. Post any questions you have, and we'll work on the answers.