You also can use the 'request' helper methods if you want as well. Here is one overload which takes the path, query, and fragment portions of the request uri:
/// <summary>
/// Asynchronously sends an HTTP request.
/// </summary>
/// <param name="mtd">HTTP request method.</param>
/// <param name="path_query_fragment">String containing the path, query, and fragment, relative to the http_client's base URI.</param>
/// <returns>An asynchronous operation that is completed once a response from the request is received.</returns>
pplx::task<http_response> request(method mtd, const utility::string_t &path_query_fragment)