To get started, navigate to Destinations in the left-hand navigation menu and click the Groups link in the Destinations drop-down.
To add a group, first, click the Add Group button at the top-right of the screen. To edit a group, find the group you wish to edit in the list of groups and click its corresponding Edit button.
Type the name of the group into the text field and then click the Create Group button to save the group, or Save Changes if you're amending a group. This will return you to the Groups screen where you should now see the newly created group.