How to redirect to another page after calling async task

I have an issue of redirecting to another page after calling a async task.

I am trying to add user by calling a async method in a class.

I need to complete this task.. please help me...

Here is my code:

public partial class createuser : System.Web.UI.Page
{
    protected void saveButton_Click(object sender, EventArgs e)
    {
            UserInfo objuserinfo = new UserInfo();
            AddUser objadduser = new AddUser();

            objuserinfo.first_name = "First Name";
            objuserinfo.last_name = "Last Name";
            objuserinfo.zip_code = "95023";

            objadduser.Main(objuserinfo);

            Response.Redirect("http://www.google.com", false);
    }
}
class UserInfo
{
    public String first_name { get; set; }
    public String last_name { get; set; }
    public String zip_code { get; set; }
}

class MessagePut
{
    public void Main(UserInfo objuser)
    {
        RunAsync(objuser).Wait();
    }

    public async Task RunAsync(UserInfo objuser)
    {
        using (var client = new HttpClient())
        {
            var apikey = "xxxxxxxxxxxxxxxxxxxxx";
            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
            client.DefaultRequestHeaders.Add("X-Apikey", string.Format("{0}", apikey));
            var username = "xxxxxxxxx";
            Uri postUrl = new Uri(string.Format("http://ift.tt/2f9R1sT", username));
            var objresponse = client.PutAsJsonAsync(postUrl, objuser).Result;
            if (objresponse.IsSuccessStatusCode)
            {
            // EXIT 
            }

        }
    }
}