To download the Amazon Alexa app, you can either search for it in your app store or you can use the following link:
• Alexa App for iOS: https://itunes.apple.com/in/app/amazon-alexa/id944011620
• Alexa App for Android: https://play.google.com/store/apps/details?id=com.amazon.dee.app
Once the app is downloaded, open it and sign in with the same Amazon account you used to set up your Alexa-enabled device.
Once you've signed in, you will be able to control your Alexa-enabled devices, listen to music, and access a variety of Alexa features. From the app, you can also view and manage your shopping and to-do lists, as well as create lists, alarms and calendars.
For more detailed instructions, you may refer to this page on Amazon's website: https://www.amazon.com/gp/help/customer/display.html?nodeId=201789040