I did not use tweetinvi for the authorisation, I have reasons for wanting to do it all manually. But once I have the access oauthtoken and the access oauthtokensecret, I set the credentials in tweetinvi and use tweetinvi for performing the twitter actions.
Is your project a Store app? or web based?
Neither, just an old fashioned windows desktop app
if store app, can tell me how to handle the callback thing, I have hard time to understand it.
as I said, it isn't a windows store app, but I would a imagine a callback, is just a method that gets called later, like an action or a func?