Download and install the Alexa app on your phone. Required to connect your Echo.
Open the App Store (iPhone) or Google Play (Android) and search for "Amazon Alexa". Download the official app — it's free.
Open Alexa and sign in with your Amazon account. If you don't have one, tap "Create a new Amazon account" — it only takes 2 minutes.
When prompted, allow Alexa access to your location and Bluetooth. These are needed to discover and connect your Echo device.