Probably the best way to know how to record a lesson or exercise is to listen to the lessons already on the site. You should hear a common theme and one that many instructors use:
- Tell them what you hope to achieve
- Perform slowly at first, then at tempo
- Finally, reinforce the purpose and conclude with your thoughts

Here's my technique:
1. Have a plan.
2. Write down what you want to say. Keep these things in mind:
 - What is the purpose of the exercise?
 - How should someone use the exercise?
 - What will be the result of the exercise?
3. Warm up before you start recording
4. Start recording
 - Read the information about your exercise to keep on track (and to avoid from fumbling with what to say)
 - Play your exercise
 - Conclude with what should be accomplished and your thoughts about the lesson

Technical stuff:
Audio - MP3 or WAV (48kbit/s 22,050hz is preferred)
Notation - PDF, Finale, JPG,or PNG file (Please transpose into all keys where applicable)
Documentation - plain text or html