Final Fantasy X-2/Chapter 1/Airship Celsius

Upon boarding the Celsius, talk to Rikku and Paine for some backstory. Then head to the front of the ship to talk to Brother for three Al Bhed Primers and a brief explanation on what Al Bhed is and how to learn it.

Next head over to Shinra. He's the little guy to the right typing at a computer. He can be extremely useful, able to provide dossiers on almost all characters you have met. He is also keeper of all the treasure spheres the girls will collect on their journey. If you like, you can currently view the sphere "Journey's Start" to learn why Yuna has embarked on her current quest. While navigating through his computer, select "Shinra's Guide to Everything" then "Using Garment Grids". Complete this tutorial to receive the Vanguard Garment Grid.

Now head up the stairs at the back of the room toward the Save Sphere through the door. Save if you wish, and then continue along the passage to the lift and choose to go to the Engine Room. Open the four chests found here for Phoenix Down x4, Ether, Remedy x3, and Potion x4. Return to the lift.

Now travel to the Cabin. Speak to Barkeep, the Hypello at the bar. He has basic items for sale. Buy items from him if you wish, and then choose to "Rest". Note that resting at least once in the Cabin during each chapter will unlock a few scenes in Chapter 5.

After resting, return to the Bridge and head to the front to hear an announcement. Now return to the bridge and walk to the front of the bridge. Talk to the pilot and then confirm your selection to head off to Mt. Gagazet.