Topic on Project:Support desk

I closed the option to add a viewed page to my travel book "Schotland 2018". How do I get the pop up window again that makes it easy to add a page to my book. Also even when I'm logged in, I cannot see my "collection" nor do I know how to "save" a book. I do not need to save and share the book but I cannot find the book as a subpage in the navigation panel either... Thanks for some feedback

Where to find that option? How to "close an option"? How to create a "travel book"? Is this https://www.mediawiki.org/wiki/Extension:PdfBook or something else? Which MediaWiki version is this about? This needs clearer steps to reproduce. :)