Have a column in your report be a link. Inside that link define
Target: Page in this application
Page: same page you're at or new page you want to go
Item 1: V_BOOK_ID Value: #BOOK_ID#
This simply technique will set the value of a column in your report called BOOK_ID to V_BOOK_ID. You can easily use Pn_BOOK_ID too even if the page for Pn_BOOK_ID is different from the page you want to go to.
I would recommend you go thorugh the "2 Day Developer Guide" (Oracle Application Express - Documentation</title><meta name="Title" content="Oracle Application…) or get an APEX book.
Hope this helps