In order to use OAuth2, you have to create an App on Reddit (https://www.reddit.com/prefs/apps/). For most use cases you will choose script
as app type. You have to set the redirect uri
to http://127.0.0.1:65010/authorize_callback
, the other fields are up to you.
Copy the oauth.txt file from repo, edit in the App Info section with data from the app you created on reddit
Edit the variables according to the comments in the file