Hi khoke,

You could do this using javascript code, similar to the following:

        function buttonClicked() {

            var grid = $find("WebDataGrid1");

            //Gets the selected row

            var selectedRow = grid.get_behaviors().get_selection().get_selectedRows(0);

            //Gets the text from the first cell of the selected row

            var firstCell = selectedRow.getItem(0).get_cell(0).get_text();

            alert(firstCell);

        }

If you have any further questions, please feel free to contact me.