'How to save .net Identity data in DB via web api

Im quite new with web development and trying to create a website on public server which will store data on a local DB server via web api. I got it working to a degree where I can post or get data from my web app. Now, I need to implement (google and WS-federation) log in mechanism so I decided to use Identity which seems to be doing majority of the things for me which is great, it creates DB with necessary tables to store log in info.

But I'm struggling to set up identity to store that data in DB via web api. Is that incorrect way of doing authorisation? I'm a bit lost on this one so any help or advice would be much appreciated.

Solution 1:^[1]

I think a good way to do that is to use tokens for validation. So that you can do Google authentication by another server and then use that token to use Web APIs.