Ah, that's it then! I didn't know that I have to get a full wheel to enable this feature. That explains it then. Once unlocked, I assume it's self-explanatory. Exactly the information I was looking for, thanks!
From what I understand, which may be incorrect, the first person to propose a third tag "gets it" - I don't believe there's a feature to vote on whether or not the community agrees with the tag or not. However, I've never actually third-tagged something so this is just an observation, not based in first-hand experience. If I'm wrong, my apologies.
There is the tag that you choose for your post, then there is the community tag. The community tag sits next to your tag and lets the readers decide what they find the topic/content to be about and label it as such. The community tag is not set in stone...whatever the most people submit as the community tag will be displayed (So I tagged this post 'hubskihelp' but if two people after me comm-tag it 'newbie' then 'newbie' will be displayed). The original poster's tag always remains though. :)
It would be nice to think so, but I'm not sure the programmers made that possible. You can go in and change the community tag to whatever you want and then I can go in and change it to whatever I want. The original poster always gets two tags that do not change. For example, by request, I just corrected the typo in this post's tags from #newtohunski to #newtohubski Perhaps someone wiser will correct me.