Here's Google's training info on Google Classroom Level 1: The Basics.
New as of September 2014, Google Classroom combines elements of social media (think Facebook or EdModo) with the files from your Google Drive and the contacts from your Gmail to let you communicate and share files with your students. It also lets you distribute, collect, and grade assignments online - no more paper!
Because it is new, there is not yet much info available on it; but if you are logged in to your school GAFE account (if you have your school Gmail open, you're logged in), you should be able to access your Classroom by going to < classroom.google.com >.