You all have missed the point. And as someone who has written several web based training programs on how to repair, maintain, and troubleshoot forklifts, you build you programs with the anwsers to the questions IN. That of course requires you to fully understand the topic and not be a bulls**t filled trainer. Sorry if I just hurt your feelings.
It requires planning but all but hands on can be done this way and with a little work most of hands on too.
Best suggestion, in breif
1) know what, in detail, you want to do (Story board time)
2) know who (or is that whom) will be taking the course
3) know how and where they will be taking the course
4) how long should they take and how long do they have

That will get you started, Then look into the dozens of different software titles. Try the and pick what works for your course. You may need to use several to complete your project, so make sure that they work with each other.

As an example of on line learning check this out http://www.georgebrown.ca/Marketing/FTCal/caet/T902.aspx

It's an on line electronics course.

Have fun, for the work is long but the result, done properly, is GREAT!