Drag one or more objects from a document window to an active Object Library panel.
Select one or more objects in a document window, and click the New Library Item button in the Object Library panel.
Select one or more objects in a document window, and choose Add Item in the Object Library panel menu.
Choose Add Items On Page [number] As Separate Objects in the Object Library panel menu to add all the objects as separate library objects.
Choose Add Items On Page [number] in the Object Library panel menu to add all the objects as one library object.
Drag an element from the Structure pane to an active Object Library panel.