Amazon has a program called - Amazon Affiliate. Join it.
Then you can link your book to your website or blog and people can buy it from you.
BONUS - Amazon will pay you (I think it is 4%) for linking to your website.
Can't beat that!
It's simple to do. Just sign up.
Then you will see a gray bar above the Amazon pages for a book or whatever you want to link to.
To add your link, or that of a friends book you want to promote, you click on - Link to this page
You will get a code to put on your website.
Now people can buy your book from Amazon on your site.
See - my book, Liberty Belle, is on the sidebar.
Happy writing, Indies.