I tried to bookmark a page, but when I clicked on bookmarks, "Bookmark This Page" was not one of the options. How can I bookmark a new page?

The '''Star''' at the right-end of the Address Bar is the '''"Bookmark this Page"''' button in Firefox 57. ''If that Star is blue, that page is already saved as a bookmark.'' The various toolbar button drop-downs don't have that menu item any longer -- except for the Menu Bar ''(hidden by default)'' '''Bookmarks''' drop-down menu. The Menu Bar can be temporarily displayed using the '''Alt''' key and then hit '''{ B }''' to open that drop-down, and you'll then see the '''Bookmark the Page''' menu item there. '''{ Ctrl + D }''' can be used from the keyboard to save a new Bookmark, too.