Hjælp med noget C#

Kode 

try
            {
                // get the first four characters from the link
                int tmp = Int32.Parse(tvwRss.SelectedNode.Index.ToString());

                // test the link text and then
                // navigate the browser to that link
                webBrowser1.Navigate(listBox1.Items[tmp].Text);
            }
            catch 
            {
                // if it is not a link, skip it
            }

Kode 

webBrowser1.Navigate(listBox1.Items[tmp].Text);