<grid grid.column="1" grid.row="1" height="177" horizontalalignment="Left" margin="10,12,0,0" name="grid3" verticalalignment="Top" width="595" datacontext="{Binding ElementName=DataEntrydataGrid, Path=SelectedItem}">
<grid.rowdefinitions>
<rowdefinition height="48*" />
<rowdefinition height="129*" />
</grid.rowdefinitions>
<grid.columndefinitions>
<columndefinition width="128*" />
<columndefinition width="467*" />
</grid.columndefinitions>
<textblock height="23" horizontalalignment="Left" margin="40,24,0,0" name="textBlock8" text="LastName" verticalalignment="Top" />
<textbox grid.column="1" height="23" horizontalalignment="Left" margin="9,21,0,0" name="LastNametextBox" verticalalignment="Top" width="120" text="{Binding Path=LastName}" />
</grid>
I just did it using databinding. no need to write any code