Changing Secondary?

I heard I can change my secondary proffession. Where can I do this? I've already reached Drok's.

I think it is in seekers passage or hero's audience I could be wrong.

thats right gosl is right ^^^

You first have to ascend. So when you finish the Sanctum Cay mission, you will be taken to the desert area. Finish ascension there, then I believe Vanyi (in Droknar's Forge) will give you a mission where you visit 3 towns in the desert. Within those towns, there will be NPC's who have the quests to change your profession. Depending on the profession, you'll need to talk to different NPC's.