Use the Lists area in Messages to configure who you want to send your message to.  Click Create Mailing List and give the list a name.

It’s recommended to create Lists based on topic/subject area rather than by people, for example, use Weekly Top stories rather than All Parents.

Add an administrator email to Status Change Email(s) to be alerted of any recipient subscription changes such as a user becoming subscribed or unsubscribed.

The Permissions tab is used to configure which administrators can edit this list.  Use the Privacy tab to configure who can subscribe to the list, the default setting is public by default, allowing everyone to subscribe.

Click on Add Subscriber to add recipients to the list.
There are four ways to add recipients to the mailing list:

Constituent - add a single user from Constituent Manager
Group - add a group/role of users from Group Manager 
Contact - manually add up to 10 email addresses 
Upload - add a list of recipients using a spreadsheet

Once recipients have been added to the list, they can be easily removed.  This is done by unsubscribing the recipient.  Click on the - far right-side of recipient email address, when the pop-up box appears, select Unsubscribe. 

To add the recipient back to the list, click on the + to Resubscribe.

Check back next week for configuring Dynamic Content