Once you have an audiobook publisher account*:
To create a new title record in NetGalley, press the Create New button on the MANAGE TITLES page. Much more detail is outlined in this article, and don't forget to Associate Other Formats you may have uploaded to NetGalley.
Once you have created your title record, you must upload your audiobook files to the FTP.
*To add audiobooks to NetGalley, you must have an audiobook publisher account. Please contact firstname.lastname@example.org if you need an audiobook login.