Once you have published your book, and it is available on Amazon, go to Author Central. The first time you use this facility, you need to click on the Join Now button on the right, and follow the on-screen prompts to set up your author account. You will receive a confirmation email with a link inside it you need to click. Then you can set up your profile, where you can enter a brief bio, blog links, connect to a twitter account, add videos and schedule events.
Once you’ve set your profile up, which should look something like this when you’re done, you can click on the Books tab at the top of the page, and search either by Author, book title or ISBN and simply tell Amazon which of the resulting finds are your titles, to add them to your author page.
After you claim your books, you can update the product descriptions and author bio, and add content to the “From the Author” section, and even add short reviews, so any blurbs you’ve collected can be shared on Amazon.
There’s also a “Book Extras” section where you can connect your title to Shelfari.com, providing a synopsios, character list and various other information that might encourage readers to look at your book.
Take a look at the Moroaica Shelfari page for an idea of the kinds of information you can add.