WPF- How to save and retrieve details from database

Question

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
<Grid>
<TextBox HorizontalAlignment="Left" Height="23" Margin="144,28,0,0" TextWrapping="Wrap" x:Name="TbxId" VerticalAlignment="Top" Width="193"/>
<TextBox HorizontalAlignment="Left" Height="23" Margin="144,134,0,0" TextWrapping="Wrap" x:Name="TbxFn" VerticalAlignment="Top" Width="193"/>
<TextBox HorizontalAlignment="Left" Height="23" Margin="144,77,0,0" TextWrapping="Wrap" x:Name="TbxLn" VerticalAlignment="Top" Width="193"/>
<Label Content="Student ID" HorizontalAlignment="Left" Margin="10,28,0,0" VerticalAlignment="Top" Width="101"/>
<Label Content="Last Name" HorizontalAlignment="Left" Margin="10,134,0,0" VerticalAlignment="Top" Width="101"/>
<Label Content="First Name" HorizontalAlignment="Left" Margin="10,77,0,0" VerticalAlignment="Top" Width="101"/>
<Button x:Name="BtnSave" Content="Save" HorizontalAlignment="Left" Margin="23,206,0,0" VerticalAlignment="Top" Width="75" />
<Button x:Name="BtnBrowse" Content="Browse" HorizontalAlignment="Left" Margin="149,206,0,0" VerticalAlignment="Top" Width="75" Click="Save"/>
<Button x:Name="BtnShow" Content="Show" HorizontalAlignment="Left" Margin="294,206,0,0" VerticalAlignment="Top" Width="75"/>
<WindowsFormsHost Grid.Column="0" Margin="448,28,75,243">
<wf:PictureBox x:Name="pictureBox1" Height="150" Width="150" SizeMode="StretchImage"/>
</WindowsFormsHost>
</Grid>

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