WPF- How to save and retrieve details from database

I want to develop an desktop app to save and retrieve details from database, but am having a little hitch
am getting errors in my code, kindly advice below are the required code

xaml















cs

private void Browse(object sender, RoutedEventArgs e)
{
SqlConnection cn = SqlConnection(global::DatabaseApp.Properties.Settings.Default.Database1ConnectionString);

try
{
OpenFileDialog dlg = new OpenFileDialog();
dlg.Filter = "JPG Files (*.jpg)|*.jpg|GIF Files (*.gif)|*.gif|All Files(*.*)|*.*";
dlg.Title = "Select Student Picture";
if (dlg.ShowDialog() == DialogResult.OK)
{
imgLoc = dlg.FileName.ToString();
picStu.ImageLocation = imgLoc;
}
}
catch(Exception ex)
{
System.Windows.MessageBox.Show(ex.Message);
}
}

Thank you