I can imagine that it is very difficult for a beginner to set up a custom rom on a device. That's exactly why I wrote at the beginning that the simplest and cheapest solution is a Google Chromecast. I don't have the time to create a picture tutorial. Custom Roms are only for hobbyists. Apps like Netflix and so on that are protected don't work there either. From ~40€ you get everything from Google that is up to date and everything works.
Chromecast mit Google TV
Chromecast with Google TV turns any TV into a smart TV with one seamless experience for all your streaming apps.
store.google.com