Web Forms :: How To Save Pdf File

I made a fuction for merging the multiple pdf file to a single one. All are fine. now after merging i can show it with open and save dialogbox. I dont want to show this one. So i just remove the suppressed the code from my code. But i want to save this one in my destination directory without asking the open and save dialogbox. So send the code for save the file with my estination(veriable) path as permenently as new one if it is exist. I exact code is bellow

{
private
string Merge(ArrayList arr,
string destinationFile)Document document =
null;PdfCopy writer =
null;try
{

//////////HttpContext.Current.Response.ContentType = "application/pdf";
//////////HttpContext.Current.Response.AppendHeader("Content-Disposition",string.Format("attachment; filename={0}",Path.GetFileName(pdf[0])) );
//////////document = new Document();..............