Google Classroom is how you can stay in contact with your students. Just click on the waffle icon and find this logo above.
*** Here is a short video I found that demonstrates very well what things look like from the STUDENT'S perspective. Click here to see this video
Here is an excellent slide deck (from Dan Niessen from NEOnet) on how to use Google Classroom, please click here.
Dan conducted a webinar teaching all the core aspects of Classroom, and made the recording available to watch here.