How to hide this dialog and save downloading file without prompt

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C#

I have a task for using web browser in windows application to download the file from web site. I use the given code for this :

webBrowser1.Document.GetElementById("loginform:userName").InnerText = Username;
webBrowser1.Document.GetElementById("loginform:password").InnerText = PassWord;
webBrowser1.Document.GetElementById("loginform:submit").InvokeMember("click");
webBrowser1.Document.GetElementsByTagName("select").GetElementsByName("Reports:j_idt44")[0].Document.GetElementsByTagName("option")[1].SetAttribute("selected", "selected");
                webBrowser1.Document.GetElementById("Reports:j_idt72:0").SetAttribute("checked", "checked");
                 webBrowser1.Document.GetElementById("Reports:j_idt75").InvokeMember("click");

After the execution the save dialog box will appear, but I dont want to show the dialog box, the file directly download. Anybody response the query.