I'm assuming you bought the book outside of Adiko? I don't know where the book downloaded so you may have to look around, but to get it on Aldiko's bookshelf you need to import it. Start Aldiko, press the home icon in the upper left corner, select sd card and find the book. When you click on a book, you'll be given the option to open it or import it, choose import and it will appear on the shelf.