WPF- How to save and retrieve details from database

<grid>
        <textbox horizontalalignment="Left" height="23" margin="144,28,0,0" textwrapping="Wrap" x:name="TbxId" verticalalignment="Top" width="193" xmlns:x="#unknown" />
        <textbox horizontalalignment="Left" height="23" margin="144,134,0,0" textwrapping="Wrap" x:name="TbxFn" verticalalignment="Top" width="193" xmlns:x="#unknown" />
        <textbox horizontalalignment="Left" height="23" margin="144,77,0,0" textwrapping="Wrap" x:name="TbxLn" verticalalignment="Top" width="193" xmlns:x="#unknown" />
        <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" xmlns:x="#unknown" xmlns:wf="#unknown" />
        </windowsformshost>
</grid>

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);
            }
        }