Existing tags can be edited by clicking on the tag to open the Edit Taxonomy Category modal. In addition to enabling the setting for public visibility, here you may also choose the option to enable subscriptions for this tag. This creates an automatic Communications Topic associated with the tag. This will become more useful as additional features are implemented.
To add a child level to an existing level, hover over an entry in the table and click the green Create a new child button. This will open another modal like the one seen above for creating this new level.
See also: