Hi NIK and welcome to MobileRead!
The Sony ebook library will not allow you to change book titles, authors or other information (meta-data). As grooks recommended, calibre will allow you to do this. It is an ebook management programme that allows you to change meta-data of books, converts books to different formats and allows you to organise your books through tags.
This is the link to the website: http://calibre.kovidgoyal.net/