Question

I am developing a windows application and I want to add a browse button to upload file and once the user chooses file or files to be uploaded (only pdf files), I want to append them in a panel, and when clicking on any file it opens in adobe reader as these files are pdf.

Answer 1

The browse button click event should be like this,

private void testButton_Click(object sender, RoutedEventArgs e)
{
    OpenFileDialog openFileDialog = new OpenFileDialog();
    openFileDialog.CheckFileExists = true;
    openFileDialog.AddExtension = true;
    openFileDialog.Multiselect = true;
    openFileDialog.Filter = "PDF files (*.pdf)|*.pdf";

    if (openFileDialog.ShowDialog() == System.Windows.Forms.DialogResult.OK)
    {
        foreach (string fileName in openFileDialog.FileNames)
        {
            Process.Start(fileName);
        }
    }
}

I am not sure about the later part of the question though. Do you want to load (open) the file or upload it? And what exactly do you want to add to the panel? A panel is simply a controls container.