To Download an application to your Kindle for the first time:
You can search and browse for apps in the Store section of Amazon Appstore for Android by tapping Apps from the Kindle Fire Home screen and selecting Store. You can search for apps by entering a search term in the search bar.
Once you've found the app you'd like to purchase, tap the orange price button and select Buy App or Get App. Your default 1-click payment method will be charged automatically (unless the app is free).
Once your app has successfully downloaded to Kindle Fire, tap the orange Open button below the "Thank you for purchasing this app" message.
After tapping Open, you'll see a prompt to agree to the developers License Agreement. Please carefully read this agreement before tapping Agree. Note: If an app was purchased from Amazon Appstore for Android on a computer, tap the Settings icon and select "Sync" before visiting the Apps Library.
After you have purchased an app from Amazon Appstore for Android, the download and installation will begin immediately when your Kindle Fire has a Wi-Fi connection.