On this demo page you can find the bookmark buttons at the upper right of each page except the bookmarks page. Just click on the bookmark button and the current page is in your bookmarks. You can manage your bookmarks via "Your Bookmarks" - located in the top navigation. More info can be found in the Manual.
You're authenticated in this demo automatically and your IP Adress is the Key. You could and should use you own authentication module.
get Simple Bookmark here