How to get access token using authorization code

When I send client ID I’ll get code in return. Further I have to use that code along with client ID & secret in order to get access token but I won’t get any in return it shows result: bad request error: not allowed

@joshiadvait8 you can check this sample app for reference GitHub - codechef-org/codechef-sample-app

Edit: Updated the sample app link.

404 page not found. I think repo has been deleted.