This repository contains LINE Login SDK for C#
See Integrating LINE Login with your web app for LINE Login detail.
Instantiate LINE Login Client
var client = new LineLoginClient(channelId, channelSecret, redirectUri, "State", Scope.Profile | Scope.OpenId);
Get Authorization URL
var authUri = client.GetAuthUri();
Get Token (AccessToken and JWT)
var code = Request.QueryString["code"];
var token = await client.GetToken(code);
I refer to following references to get basic coding idea.