You can specify that alerts be sent either to groups of users or to individual users.

Group Recipients
  Specify that this alert be sent to a group or groups of users. Select each group from the left list, Available Groups, then click the "Add to List" button. The group will be moved to the Current Groups list on the right. To remove a group from the Current Groups, click the "Remove from List" button.
User Recipients
  Specify that this alert be sent to an individual user or several individual users. Select each user from the left list, Available Users, then click the "Add to List" button. The user will be moved to the Current Users list on the right. To remove a user from the Current Users, click the "Remove from List" button.

When you are done, click the Save button, or click Cancel to discard your changes.