以下の手順で認証を設定する方法がわかりません
static string _address = "http://Foo.table.core.windows.net/BackupEntries()?select=RowKey";
static void Main(string[] args)
{
// Create an HttpClient instance
HttpClient client = new HttpClient();
client.DefaultRequestHeaders.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("aa", "");