Start here. When you create your (free and 5 seconds to make) account, your basic dashboard looks like this:
You can add a picture and a few details to your profile. You can join groups (you might notice I've joined the Edmodo New User Group) or create groups. For use in your classroom, you'll want to create groups for your class as a whole group, by subject, or maybe even by reading or word study groups.
You can then add assignments:
Quizzes: (That can be automatically graded. Time saver!)
Keep track of grades:
And store files in your library so you can access them for other assignments and posts:
For more information, I highly encourage you to visit the Edmodo Blog and watch several of the webinars that are available to view at any time.
Excited yet? Who wants to use this in their classroom this year?!