Azure DevOps Wiki API

using Newtonsoft.Json;
using System;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;

namespace ConsoleApp1
{
    class Program
    {
        public static string personalAccessToken = "your_personal_token";
        public static string path = "/Test";

        public class request
        {
            public string content { get; set; }
        }

        static void Main(string[] args)
        {
            using (var client = new HttpClient())
            {
                request req = new request { content = "New content for page" };
                var jsonString = JsonConvert.SerializeObject(req);
                var httpContent = new StringContent(jsonString, Encoding.UTF8, "application/json");

                client.BaseAddress = new Uri("https://dev.azure.com");
                client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic",
                Convert.ToBase64String(
                    System.Text.ASCIIEncoding.ASCII.GetBytes(
                        string.Format("{0}:{1}", "", personalAccessToken))));

                var response = client.PutAsync("/duranhsieh/Bupa Demo/_apis/wiki/wikis/TestDemo.wiki/pages?path=" + path + "&api-version=5.0", httpContent).Result;

                if (response.IsSuccessStatusCode)
                {
                    Console.WriteLine("Success");
                }
                else
                {
                    Console.WriteLine("Error");
                }  
            }
        }
    }
}