OAuth 1.0 default request token URL?

I have created a POST query that works in Postman using OAuth 1.0 authentication.
I only provided one url:

How does postman know all other urls - to request token etc.
I’m trying to rewrite in a custom C# app but have no idea how to track what happens when I click send - if I go to Developer Console I only see the final request with final params that were obtained somewhere?


You tell Postman which URL to use when requesting the token.