https://developer.android.com/things/hardware/raspberrypi
Download the Console Tools from the following link. You will need to sign into your Google account.
https://partner.android.com/things/console/#/tools
Unzip the file and Launch the correct utility for your OS.
On Windows you will need to launch as administrator by right clicking on the Windows Application and Run as administrator.
The program is easy to follow along with and automatically downloads and creates the SD card for the Pi.
After you are finished, put the card in the Pi and boot it up.