Notify when a particular streamer starts broadcasting

Nice to meet you, my hobby is to make any app using C# while reading the reference book.
Now I’m trying to make an app that will notify when one broadcaster starts a live.
However, I can’t use the API because I don’t know how to get the OAuth token (?).
Can you give me some advice?
Since I don’t understand much except C#, I am sorry to trouble you, but it would be very helpful if you could give me the sample code.

Authentication is covered here

you probably want an “App Access Token” as described

Sorry for the late reply, thank you for your help in using the API.