Guild Wars 2

How can we earn it?

for what i have played so far, each time you get one level in a mastery you also earn 1 mastery point. although i didn’t play that much in tyria these past few days so i wouldn’t know if doing events reward any points.
although in your achievement panel you can find some achievement will award you also with a mastery point. maybe you should try that.
if i understood correctly to unlock the mastery tracks you have to own HOT, so there are mastery nodes there