The first thing to do is install OBS. It is the standard when it comes to streaming. There are tools built on top of it, but typically I recommend using bare-bones OBS or Streamlabs OBS (SLOBS) which is OBS with some plugins from Streamlabs.
The main reason to use OBS or SLOBS is more flexibility when streaming, and as far as I know, OBS is the only one that allows you to stream closed captioning.
For the remainder of the post, I will refer to just OBS instead of OBS/SLOBS.
I won't do a deep dive into all the things you can do with OBS, but know that you can create scenes with many sources. A scene can be for example a starting soon page, and when you're ready to start talking you transition to another scene, perhaps called chatting or coding view.
There are many sources you can add to a scene:
browser sources, e.g. a web page used for an overlay in your stream
It's important to go over your setup before going live on a stream. You want to make sure audio is good, video etc. Here is a sample checklist that I created for the purpose of this post. It's a reduced version of my own checklist.
Turn off notifications for any software on laptop
Ensure closed captioning is working with OBS
Check audio is not muted and is working for you and your guests
Have Twitch chat open in a browser or the entire stream (make sure stream is muted!)