// File upload control
              <asp:FileUpload ID="FileUpload2" runat="Server" />
              
    // Fires when Button is clicked.
    protected void UploadFileOnServer(object sender, EventArgs e)
    {
        // limitation of maximum file size
        int intFileSizeLimit = 10;

        // get the full path of your computer
        string strFileNameWithPath = FileUpload1.PostedFile.FileName;
        // get the extension name of the file
        string strExtensionName = System.IO.Path.GetExtension(strFileNameWithPath);
        // get the filename of user file
        string strFileName = System.IO.Path.GetFileName(strFileNameWithPath);
        // get the file size
        int intFileSize = FileUpload1.PostedFile.ContentLength / 1024; // convert into byte

        // Restrict the user to upload only .gif or .jpg file
        strExtensionName = strExtensionName.ToLower();
        if (strExtensionName.Equals(".jpg") || strExtensionName.Equals(".gif"))
        {
            // Rstrict the File Size 
            if (intFileSize < intFileSizeLimit)
            {
                // upload the file on the server
                // you can save the file with any name, However as this is the sample so I have saved the file same name for all users. So it will overwrite your file with next user's who will test this tutorials.
                FileUpload1.PostedFile.SaveAs(Server.MapPath("~/UserFiles/Samples/") + "SampeFromTutorials" + strExtensionName);

                lblMessage.Text = "Uploaded file details <hr />" +
                    "File path on your Computer: " + strFileNameWithPath + "<br />" +
                    "File Name: " + strFileName + "<br />" +
                    "File Extension Name: " + strExtensionName + "<br />" +
                    "File Size: " + intFileSize.ToString();
            }
            else
            {
                lblMessage.Text = "File size exceeded than limit " + intFileSizeLimit + " KB, Please upload smaller file.";
            }
        }
        else
        {
            lblMessage.Text = "Only .jpg or .gif file are allowed, try again!";
            lblMessage.ForeColor = System.Drawing.Color.Red;
        }
    }