Add new product to Amazon

I have a number of products, books and DVDs, being sold from my Amazon page. I want to add a hardcover version of one of my books currently available on Amazon only as a paperback and an e-book. I understand the basic procedures for doing this through Amazon Seller Central but somehow can't seem to make it work. Looking for a bit of help on adding this version to an existing site. If this works out okay there will be some other tasks associated with social media.