Problem in getting selected data in datagrid...!!!

hello friend..

i have one query ..

i have 3 table

for ex

1. tblproduct
2.tblproductoptionM
3.tblproductoptionD

on my product page is load the joined data from tblproductoptionM and tblproductoptionD
into datagrid with id , name and textbox with 3-4 rows

my question is i want the perticular data inserted into tblproduct and tblproductoptionD back to the page for updation here in datagrid ex. 2 rows have the data so i want that data to be selected -- that is bit difficult for me to work

the tblproduct productid is thr in tblproductoptionD

i work on object base classes

tried with iterating the loop by foreach (tblproductoptionD objpod in object of tblproduct.list){}

i dnt knw the property of selected row in datagrid

help me out..

thank you.