Simple example of Alexa skill.
To start you need to configure AWS cli and your credentials on AWS see here. You also need to have configured Alexa skill see here.
After that, fill your Alexa skill id into serverless.yml to Alexa event in Alexa function (replace amzn1.ask.skill.fde3.......... with your id).
Now you can run npm run deploy:staging.
After that, log to your AWS console and copy your lambda id into your Alexa console (you need to open your skill and in Endpoint fill in your lambda id).