Final Draft will allow you to import your novel and other books in PDF, RTF or TXT format via these steps:
Importing a script from another program such as Word
However, Final Draft is not able to automatically reformat your novel as a screenplay. Novel writing and screenwriting are very different disciplines. You'd need to rewrite the imported document to match expected screenwriting conventions, as well as Final Draft's built-in formatting tools to format elements like Action, Character, Dialogue, etc.
For more info on using the formatting tools, click here: