Index: backgrounds;inserting from Gallery gives you the page
Title: Inserting Objects From the Gallery
That page needs an update. Gallery was integrated in the Sidebar long time ago and the symbol was removed from the default settings of the Standard toolbar.
The described way to link an image from the Gallery has been removed by purpose.
Insert as background of an object does not work as described.
The item Gallery has been moved from the menu Tools to the menu View.