Online requirements:
- You need an account on some streaming website like twitch.tv/livestream.com/hitbox.tv, etc.
- Broadcasting software. Usually the sites will recommend one for you and give you the link (e.g. XSplit or Open Broadcaster Software <- my personal favorite)
- A fast CPU (...and this next part is obvious...but you should also have a decent internet speed, and not be using WiFi lol)
- A good data plan (you're gonna be uploading a lot of gigabytes lol)
- A webcam and mic (optional)
The software is pretty easy to understand. You basically just select the window(s) you want to stream and click Start Broadcast.
I'm not that experienced with console streaming so can't give advice there.