Guild Wars 2

So, I’ve spent over 3 hours trying to figure out the answer to my question and nothing. So here it is:

I have the mastery points for Central Tyria but, it’s not unlocked. How do I unlock Central Tyria so I can use the mastery points??

Are you in a Central Tyria zone? Also, have you done the first part of HoT to unlock the Mastery system?