After you aid the Hearer in Spirithold, Miounne asks you to go to Bentbranch.
This quest is only available if you started the game in Gridania, you have completed the quest Spirithold Broken, and have reached level 10.
Unlocking Other Combat Classes
Now that you are level 10, if you have completed your level 10 job quest for your current job (available in your job's guild), you can unlock other combat classes by talking to the Guild Receptionists in the various guilds in Ul'dah, Limsa Lominsa, and Gridania.
Starting the Quest
To start the quest, talk to Miounne in the Gridania.
Speak with Keitha
Go to the Central Shroud. You can get there by going southeast from the Carline Canopy, or you can use the main aetheryte of Gridania to go there directly if you have attuned to all aetherytes in Gridania. Or you can talk to the Chocobokeep just outside of the Carline Canopy and pay a small amount of gil to ride a chocobo to your destination.
In the Central Shroud, go southwest to reach the green checkmark on your map and minimap.
There is a large aetheryte crystal here in Bentbranch Meadows. Attune to it. If this is the first aetheryte outside of Gridania that you have attuned to, you will learn the Teleport spell. You can use Teleport to go to any of the large aetherytes that you have attuned to so far. However, it costs gil to use the Teleport spell, and you probably don't have a lot of gil right now, so you might not want to teleport anywhere just yet.
After you attune to the Bentbranch Meadows aetheryte and learn Teleport, go to the green checkmark to find Keitha. Talk to her and there will be a cutscene.
Next Main Scenario Quest
After completing the quest, talk to Keitha to accept the next quest: You Shall Not Trespass.