Email Manager Main Screen
For Email Settings -- see below
For Email History List Settings -- go here
For Item Update Actions -- go here
For how to use Email Manager to send emails -- go here
Configuring Email Settings
From: Specify "From Address" here. Multiple addresses can be entered separated by a semi-colon. When email is sent from a list item using the Email Manager, the first entry in the list below shows up as the default, but that can be changed at the time of mailing
To & CC: The icon at end of row 
opens the Recipients screen, where the To and CC can be chosen. Multiple entries can be made in any of the three options:
Default Mail Template: Select the mail template that will be shown by default when sending an email. Configure templates using the cog icon 
at the end of this row.
See this section of the manual for details: Mail Templates