What is a one-sentence summary of the following article?
Tap the Google Play Books app icon, which resembles a blue triangle on a white box. Doing so opens the main Google Play Books page if you're logged in.  If you aren't logged in, select your Google Account when prompted. If you don't have the Google Play Books app, you can download it from the Google Play Store for free. If you don't have any books in your library, you'll need to buy at least one before you can download it. To do so:  Tap {"smallUrl":"https:\/\/www.wikihow.com\/images\/e\/ea\/Macspotlight.png","bigUrl":"\/images\/thumb\/e\/ea\/Macspotlight.png\/30px-Macspotlight.png","smallWidth":460,"smallHeight":460,"bigWidth":"30","bigHeight":"30","licensing":"<div class=\"mw-parser-output\"><p>I edited this screenshot of a Mac icon.\n<\/p><p>License: <a rel=\"nofollow\" class=\"external text\" href=\"http:\/\/en.wikipedia.org\/wiki\/Fair_use\">Fair Use<\/a><br>\n<\/p><\/div>"} at the top of the screen (this may instead be a text field). Type an author, title, or keyword in the search field. Select a book by tapping it. Tap FREE SAMPLE to download a sample of the book, or tap the book's price to purchase the book. Confirm the purchase and enter any required payment details. It's at the bottom of the screen. Doing so opens a list of your downloaded books. Scroll through your library until you find a book which you want to download onto your Android. It's in the lower-right corner of a book's icon. Tapping it prompts a pop-up menu to appear. You'll find this option in the pop-up menu. Selecting it prompts the book to download onto your Android smartphone or tablet. You can now read your book whenever you want, including when you have no Internet or cellular service.

Summary:
Open  Google Play Books. Add a book to your library if necessary. Tap the Library tab. Find a book to download. Tap ⋮. Tap Download.