when checkboxes is selected the data should be store in two tables

Question

hi, iam using asp.net with c#, with sql server 2000
 
in my gridview  iam displaying data from view at page load event
the  1st column is checkbox in template field,2nd is categorynamee,3rd is itemkey, 4th is itemkeyname
5th is currentqty, 6th is salesprice,7th is quantity, 8th is total
 
i have to insert into two tables

1st table orders
 
orderno  int primary key autoincrement,
 username   nvarchar(50) ,
 shopname    nvarchar(50),
  email       nvarchar(100)

2nd table is Orderdetails
serialno   int primarykey   autoincrement,

orderno     int  foreignkey,
categorynamee     nvarchar(50),
itemkey       nvarchar(50),
itemkeyname    nvarchar(50),
currentqty      decimal,
 salesprice         decimal,
quantity          int,
 total             decimal 
 
when user selects any no of  the checkboxes that rows should be added in both tables, iam getting errors
can you give examples which helps me