Guild Wars 2

How do I unlock the Mist champion reward tracks? I hover over the lock and it doesn’t say how to unlock them. The mini champion tracks say do the hero ones first, but I can’t do the hero ones because they’re both locked. What am I missing in order to unlock them?

Enter the PvP lobby, and open up your PvP build tab. Then go to the last catagory, Mist Champions. Right click on the hero whose track you want to unlock and click buy. It costs 15 gold for each champion.

Thanks Meroim for the explanation : this is actually was of the most obscure mechanism in the whole game (i would never have found out how to unlock those tracks by myself).