An Audience is a group or segment of the contacts list that you may want to target.
Create an Audience
To create an audience, click on the Audiences link and the click the Create New link.
Add a Name for the audience and click the Create button when you are done.
Adding Contacts to an Audience
In the 'Audience' page, click the Contacts link for the Audience.
In the 'Contacts in Audience' page, click the Add New link to add a contact to the Audience.
Add the contact email and click the Create button when you are done.
You can add other Contacts to the audience in a similar fashion.