Saving as Unread
"Read later" is the option that allows you to save a bookmark to your library as "unread" so even if you don't have time to read something now, you can easily find and read it later. There are two ways to save a page as unread. The first is to simply click the read later icon on the toolbar. This saves the bookmark with default settings as well as saving as unread. The other way to save a bookmark as unread, is to bookmark the page by clicking "Bookmark" on the toolbar and checking "Read Later" on the bookmark options dialog, under "More Options".
When you want to find and read your unread items, you can do it one of three ways. The first and easiest is to simply choose "Unread" from the toolbar. A menu will open listing your unread items. The second is to open the sidebar and check the "Unread" check-box. The third is to navigate to your library and choose "Filter", then select "Unread".