Upload File to the Telegram – Telegram API

The referenced link is in TL language. I have implemented a sample to find file_id and send it to a specified user in C# using TLSharp:

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using TeleSharp.TL;
using TLSharp.Core;
using TLSharp.Core.Utils;
namespace TLSharpTest
{
    class Program
    {
        static void Main(string[] args)
        {
            Task.Run(async () => { await doTask(); });
            Console.ReadLine();
        }
        static async Task doTask()
        {
            var apiId = 87654321; //apiId: get from https://my.telegram.org/apps
            var apiHash = "<apiHash>"; // get from https://my.telegram.org/apps
            var client = new TelegramClient(apiId, apiHash);
            await client.ConnectAsync();

            var phone = "<phone_number>";
            var hash = await client.SendCodeRequestAsync(phone);
            var code = "<sent_code_by_telegram>";
            var user = await client.MakeAuthAsync(phone, hash, code);

            //get available contacts
            var result = await client.GetContactsAsync();    
            //find recipient in contacts
            var specifiedUser = result.users.lists
                    .Where(x => x.GetType() == typeof(TLUser))
                    .Cast<TLUser>()
                    .FirstOrDefault(x => x.phone == "<recipient_phone>");
            // send file to the specified contact (sample from TLSharp github)
            var fileResult = (TLInputFile)await client.UploadFile("cat.jpg", new StreamReader("data/cat.jpg"));
            await client.SendUploadedPhoto(new TLInputPeerUser() { user_id = specifiedUser.id }, fileResult, "kitty");
        }
    }
}