In gvweeklysum_RowDataBound, add click event for each of the cell...
something like this
protected void gvweeklysum_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
e.Row.Cells[0].Attributes.Add("onClick", "alert('Cell 0 Clicked');");
e.Row.Cells[1].Attributes.Add("onClick", "alert('Cell 1 Clicked');");
}
}