protected void CreateUser_Click(object sender, EventArgs e)
{
    var manager = Context.GetOwinContext().GetUserManager<ApplicationUserManager>();
    var signInManager = Context.GetOwinContext().Get<ApplicationSignInManager>();
    var user = new ApplicationUser() { UserName = Email.Text, Email = Email.Text };
    IdentityResult result = manager.Create(user, Password.Text);
    if (result.Succeeded)
    {
        SqlConnection con = new SqlConnection();

        con.ConnectionString = @"Data Source=(localdb)MSSQLLocalDB;Initial Catalog=aspnet-WebApplication1-20170217113247;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=True;ApplicationIntent=ReadWrite;MultiSubnetFailover=False";


        UserID=....

        string query = "insert into AspNetUserRoles(UserId,RoleId) values ("+ UserID + "," + "1" + ")";

        SqlCommand cmd1 = new SqlCommand(query, con);
        con.Open();
        cmd1.ExecuteNonQuery();
        con.Close();


        signInManager.SignIn( user, isPersistent: false, rememberBrowser: false);
        IdentityHelper.RedirectToReturnUrl(Request.QueryString["ReturnUrl"], Response);
    }
    else
    {
        ErrorMessage.Text = result.Errors.FirstOrDefault();
    }
}

var roleresult = UserManager.AddToRole(user.Id, "Administrator");