The email you use to log in to your school Chromebook can be used to communicate with others at the school through Gmail. You can access it by going to www.gmail.com and signing in with your school account, or by clicking its icon on the bottom shelf:
Once opened, Gmail will look something like this:
Messages and notifications will appear in the center, where it currently says No new mail!. When you receive a message, you can click it to read it, then click Reply to send a reply. To send a new email, click the Compose button in the upper left, near the Gmail logo.
Type the name or email address of the person you want to contact where it says To. Then, write a short but descriptive Subject in the line below, such as "Question about summer book club". Finally, write your message in the space below that, then click Send to send the email.