The List / Group List screen displays all individual emails and groups of emails plus allows drag and drop operations to add or remove members.
To add an individual email to a group drag from the left side of the screen to the right and drop on a group of a member of a group. To remove a individual email from a group drag from the right to the left side of the screen and drop over any position on the left.
Groups are initially created on the screen Define / Email Group.