You defeated the re-summoned Garuda, and so you move on to the final of the three re-summoned primals, Titan.
This quest is available if you have completed the quest In for Garuda Awakening.
Starting the Quest
Talk to Y'shtola in the Waking Sands in Vesper Bay in Western Thanalan to begin the quest.
Speak with R'ashaht Rhiki
Go to Limsa Lominsa and use an aetheryte to go to the Aftcastle. Go east from the aetheryte to reach Maelstrom Command. Talk to R'ashaht Rhiki there to proceed.
Attune to the Aetheryte
Go to Outer La Noscea and go to where the orange arrow is pointing on the minimap. Be sure to zoom in on the map if you are lost in the mines, so you can see which way to go. Check on the U'Ghamaro Aetheryte. This will unlock the duty The Navel (Hard).
The Navel (Hard)
Use the Duty Finder to enter The Navel (Hard). Please see the The Navel (Hard) Guide for a walkthrough.
After you complete The Navel (Hard), you will be able to proceed with the main scenario quest Good Intentions.
You can also accept the quest "Primal Awakening" from Urianger, which unlocks the Binding Coil of Bahamut in the Raids section of the Duty Finder. These optional 8-player dungeons are worthwhile to learn more of the story of the Calamity.