Save uploaded file to Sub-Domain folder in ASP.Net C#

hi,

i am using this code to upload file in my directory in my website, the problem is now i am moving the images folder on sub domain so how can i give root path like abc.com/dynamicimage  path to file to upload instead of ~/dynamicimage

here is my existing code

 protected void Upload(object sender, EventArgs e)
    {
        //if (GridView1.Rows.Count > 0)
        //{
        //    Label7.Visible = true;
        //}

        // Upload Original Image Here
        string uploadFileName = "";
        string uploadFilePath = "";
        if (FileUpload1.HasFile)
        {
            string ext = Path.GetExtension(FileUpload1.FileName).ToLower();
            if (ext == ".jpg" || ext == ".jpeg" || ext == ".gif" || ext == ".png")
            {

                System.Drawing.Image img = System.Drawing.Image.FromStream(FileUpload1.PostedFile.InputStream);
                int height = img.Height;
                int width = img.Width;
                decimal size = Math.Round(((decimal)FileUpload1.PostedFile.ContentLength / (decimal)1024), 2);

                //if (height != 600 && width != 560)
                //{
                //    Label2.Visible = true;
                //    Label2.Text =  "Image dimension should be height = 600 && width = 560";

                //}

                //else
                //{
                    uploadFileName = Guid.NewGuid().ToString() + ext;
                    uploadFilePath = Path.Combine(Server.MapPath("~/DynamicImage"), uploadFileName);
                    try
                    {
                        FileUpload1.SaveAs(uploadFilePath);
                        Image1.ImageUrl = "~/DynamicImage/" + uploadFileName;



                    }
                    catch (Exception ex)
                    {
                        Label2.Text = ex.Message;
                    }
                //}
            }

            else
            {
                Label2.Text = "Only .jpg allowed";

            }

        }


    }