Edmodo offers various resources to help you get started, including security best practices, sample guidelines and a sample code of conduct for your students.
Interesting article on how apps are being trailed in classrooms in 2013. Five apps are recommended and I have had positive experiences with Edmodo in particular as it is being used by my sons teachers.
Thanks Taylor. I saw some of your suggestions too and am adding your Brain pop resource to my tool belt. I have seen this used in classrooms- very effective on smart boards especially for visual and kinaesthetic learners. I saw Brain pop used for a Unit on 'tall buildings'. The explanations, quiz, printout and games were a very engaging part of the lesson.