If you are new to Google Classroom you will need to login for the first time. There are a couple of ways to locate Google Classroom. The Apps Chooser, otherwise known as the “Waffle” has a Google Classroom icon…. waaaay at the bottom. So for Google Classroom login for the first time you’ll need to scroll all the way down past the other app choices. The other choice is to go to:
Signed In with Your Google Account
Google Classroom does require a Google Account. You might want to already be signed into your Google account before going to Classroom. Start with http://drive.google.com to ensure you’re logged in. This will allow you to use the “Waffle” apps chooser to find Google Classroom.
Check the Account
You may be logged in with multiple accounts. Be sure that you are logging into Classroom with your SCHOOL account.
You are a TEACHER

It is super important that you choose TEACHER when prompted. It is not a fun process to have to get your Google Apps Admin to switch your roll to teacher if you select student.
Add a Class
In the upper right is a plus icon to allow you to add or join a class. As a teacher you can join a class as a student or you can create a new class.

Teachers Can Be Students
Teachers can be students. Students can be teachers IF they are a co-teacher. Students can not make their own class.
Navigate Classroom
Look for the 3 lines menu in the upper left corner. This will allow you to get back to the Home page “Classes.” Click on the title of the class in the class tile to open the class.