If you want to send out emails to your mailing lists, first you need to create the content of the emails.
To get started, click Marketing in the left sidebar menu and then choose Email Templates. Click on the Create Email Template button.
You can add the name of the template and the way your name appears to the recipients, the email subject and text. You can edit the unsubscribe text or leave it as the default (which is translated into all of the supported languages). Click Save, or just Preview to see how the changes look without saving.