I am trying to show a PopUp to Save a file and the user has to choose the destination and change file type if he actually needs. I read many articles still not getting clear idea of what to do since I am new to .Net.
 This is the code.When I run the code and click link buttons in grid view the file will be downloaded without popup and without even asking User's permission where the downloaded files must be saved

```
    protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
    {
        if(e.CommandName == "Download")
        {
            Response.Clear();
            Response.ContentType = "application/octet-stream";
            Response.AppendHeader("content-disposition","attachment; filename=" + e.CommandArgument);
            Response.TransmitFile(Server.MapPath("~/UploadedFiles/") + e.CommandArgument);
            Response.End();

        }

    }

```

I need the following to be achieved.

* Display a SaveAs File dialog Box
* The type of file should automatically be displayed in SaveAs dialog box.Eg if the type of file is image then in SaveAs dialog box .jpg should be automatically displayed. 
I have attached image of my output here
![enter image description here](https://i.stack.imgur.com/0MbFe.png)
I am not really clear with this concept.Please help Thanks in advance