This is the way I prepare books I'll alter.
Take an ordinary book, glue (you can use Elmers glue or other of your choice), some paper sheets (not too heavy), foam roller.
Take 2 or tree pages from the book you will alter and glue the first page with the foam roller.
Lay a sheet of paper over it and press well, maybe with an old credit card.
Then glue the three pages together with this sheet (see picture above).
Make this on the entire book (see pic).
When you have finished that, cut pieces of paper and glue them over the pages which have not been glued before.
Now you can paint the cover and embellish it.