Go to the Account menu and click "Manage tags".
This screen will allow you to create Tag Groups & Tags.
Create a Tag Group by clicking the "Create Tag Group" button.
Expand the groups to view tags. You can create new tags by clicking "Create Tag" or by doing it on the fly (we'll get to that in a moment!)
Ungrouped tags are ones that don't belong to a tag group.
Hover over the row you'd like to edit and click Actions > Edit.
You can change a tag's group by clicking into the "Tag Group" dropdown and selecting the new group.