You can use this library when you want to tweet other CsharpApplication.This is simple POST method code.
Input your four API Tokenkey and please write this code
using System.Twitter;
Tweet method example
var twitter = new TwitterAPI(ConsumerKey,ConsumerKeySecret,AccessToken,AccessTokenSecret);
var tweetValue = "HELLO"; //or Textbox.text and so on
twitter.Tweet(tweetValue); //tweet value