First, download Alexa app in your device for Alexa setup. Alexa app is very smart due to its features and skills. Alexa app setup is needed because without it you can't use Amazon echo dot or another device properly.
After install Alexa app, go to Alexa.amazon.com for Alexa login. Add your information in the Amazon Alexa app and ready to Amazon echo dot setup. Here, you will know the steps
for echo setup, Alexa dot setup, and echo dot setup at one place.