The best way to learn how to teach with Elluminate would start with going to a seminar or a Bytes of Technology session. Since schedules do not always allow that here are some steps to self-learn.
Elluminate calls the student role "Participant". Participant training for version 8 can be found here. The "Online Orientation" is a quick Javascript-popup walkthrough that is worth your time. Watch the "Participant Orientation" video - it's a recorded Elluminate session that explains Elluminate using Elluminate. Finally, print out the User Guide and Quick Reference.
If you're not sure you have the student role down, visit Pam Hegg or John Stryker during their online office hours. These are held with Elluminate and will give you more practice in being a student. It's important to understand what your students see so that you can give them the best experience possible.
Just as students are called "Participants", instructors are called "Moderators". Online Moderator training is here. Again, watch the recorded Elluminate session. Download and read the various User Guides and other PDFs. Finally, further down on the page is extensive help targeted to the many specific features that are available. You'll find that you won't be using all of the features of Elluminate, but you'll find help for whichever features you do use here.
There's a three-session training sequence for Moderators as well; registration is here. I do recommend that you sit through it. It's another chance for you to experience the real-world of Elluminate, and here the Moderator will be an expert ready to answer any of your questions. Take advantage of this opportunity.