how do you unlock heros?

I was wondering if anyone could tell me how you unlock heros for one on one pvp?

priest of balthazar, first tab

You have to own Nightfall to do the Hero Battles though, not sure if owning GW:EN will allow it, but it may. Either get the heroes from PvE (unlocks that hero for any PvP character), or use Balthazar Faction at a Priest. Unlocking a hero at a Priest of Balthazar will not allow that hero to be used in PvE until you complete the appropriate quest with the character in PvE.