How to use the presence web api?

I am designing a python program to automatically send a message in discord when you log on to a game, so obviously I'm going to use the presence web API. Though one issue, I have looked at the documentation and followed their instructions and still haven't been able to get it working because of one issue, authentication, I've seen the authentication web API documentation but I don't understand it. How exactly can I authenticate with the presence web API?