Your child was provided with a secure login and password that is unique to them.
Check with his/her teacher to obtain this private information OR ask them to add you as a parent via email (this will not get you access to the classroom, only weekly summary of anything assigned through Google Classroom)
Step 1: Log in to the Chrome browser with the student's user name and password
Username: xxxxxxx@school.ecsd.net
Password: unique password
Step 2: Navigate to classroom.google.com
Check out this detailed guide on navigating Google Classroom: Parent Google Classroom Guide.pdf