You can start the quest by interacting with the Sage Stone in Hearthwind Vale. The Sage Stone is on the southern coast. To get to it you need to repair the Hearthwind Vale wooden bridge.
||I found a Sage Stone in Hearthwind Vale. The Stone has tasked me to prove myself before it'll open...
The task is to wear a new outfit. You need to change 3 pieces of your clothing or accessories.
Talk to the Sage Stone in your new clothes or accessories to complete the quest and access the teleport.
Completing this and every other Sage Stone quest unlocks Rock of Sages steam achievement.