Thank you for posting. We're striving to improve the reading experience and your input is valuable.
While reading a book, every page will have a + in the top right corner of the page. You can see it on the third phone here (http://www.barnesandnoble.com/u/nook-for-android/379002287/?).
If a user clicks on that top right corner, it will add a bookmark.
Thanks for the tip on creating book marks. Is there a method for removing bookmarks already created?