Go to the web page for the book on Leanpub.
Click the blue button to add the book to your cart.
Click the blue "Continue" button.
Fill out the purchase form to pay with a Visa or MasterCard credit card, or click the button to pay with PayPal.
After you have completed your purchase, you will be taken to a web page where you can download the book. You will also receive an email with download links to download the book, and a link to the Leanpub Library we will create for you, where you can download the book again any time. (After you complete your first Leanpub purchase, you can go to your Leanpub library here.)
If you're interested in what file formats our ebooks come in, please read this: http://help.leanpub.com/reader-help/what-ebook-formats-does-leanpub-publish.
If you are buying a book you would like to share with your team, please read this: http://help.leanpub.com/en/articles/110739-i-would-like-to-purchase-a-book-for-my-company-am-i-allowed-to-distribute-the-ebook-to-multiple-people.