You can only do this using Amazon Music, as Spotify doesn't afford you that control using voice - although there are IFTTT applets out there that can can add songs played by Alexa to a Spotify playlist. Making and editing playlists with Alexa is simple, and you can do it all with your voice. If you want to create your very own music playlist using Alexa, and fill it up with bangers as you hear them, you're in luck.