There is a chapter on using emails and CiviMail in the online book Understanding CiviCRM.
CiviMail is built to work with Groups which have been set up to be used for Mailing Lists, though there is a workaround that can be used from 'more actions' from any of the Search Results screens.
The core of the process is that you first identify your target audience, then construct or import the email, then TEST the email, then schedule or send it.
The CiviMail includes opt-out and unsubscribe links.
Each CiviMailing has a report of bounces, opened, clickthroughs etc.