The layout of the first floor is pretty simple. The central stairs lead to the Sleep Blade on floor B1A. The stairs north lead to a walkway that encircles the floor. There's 400 gil in a chest to the west. A detour to the northeast stairs leads you to the rest of B1A's Treasures, as well as Cid and Princess Hilda. Follow the walkway to its conclusion to find the stairs the B1B.