var server = new HttpServer(new[]{"http://localhost:5001/"},"c:\tmp\wwwroot"
//if you want to wait
server.StartAsync().wait();

//if you want to run it and continue
server.Start();

//ASYNC Function
await server.StartAsync();

var server = new HttpServer(new[]{"http://localhost:5001/"},"c:\tmp\wwwroot")
server.ServerError+=OnServerError;
server.ServerLog+=OnServerLog;
await server.StartAsync();

...
private static void OnServerLog(object sender, ServerStatusEventArgs e)
{
  Console.WriteLine(e.Message);
}

private static void OnServerError(object sender, ServerStartErrorEventArgs e)
{
  Console.WriteLine(e.Message);
}

 server.PreResponseHandler += OnPreHandler;
 server.PreRequestException += OnPreHandlerException;
 ...
 private static void OnPreHandler(object sender, ServerPreRequestHandlerEventArgs e)
 {
     switch (e.Request.Url.LocalPath)
     {
         case "/api":
             var obj = new { message = "halloX" };
             e.ContentToSend = JsonConvert.SerializeObject(obj);
             e.Handled = true;
             break;
         default:
             e.Handled = false;
             break;
     }
 }