You can download Burner for Android in the Google Play store.
Once you download you can click "Take the tour" or "Get started".
Next you'll be asked to verify for your phone number. Your phone number will be used to complete inbound and outbound calls, so it is important that you provide your real mobile number. Your real mobile number will never be revealed to anyone you communicate with via Burner. Once you enter the verification code you'll receive via SMS, you'll be ready to create you first Burner.