Transaction Scope

Hello
I am trying to run a program to check for transaction scope
I have written the following code.
But it seems I need to add a namespace or reference
What namespace am I supposed to add

thanks


using (TransactionScope scope = new TransactionScope(TransactionScope.Required, options))
{
SqlConnection MyCon = new SqlConnection("server=hemalatha\sqlexpress;integrated security=sspi;database=demo");
MyCon.Open();
SqlCommand Mycmd=new SqlCommand("insert into t1 values 574,'scope','10/10/2007',3,3,3");
Mycmd.ExecuteNonQuery();
SqlConnection MyCon1 = new SqlConnection("server=hemalatha\sqlexpress;integrated security=sspi;database=persons");
MyCon1.Open();
SqlCommand Mycmd1 = new SqlCommand("insert into persons values 'scope',123,123,12,'scope'");
Mycmd1.ExecuteNonQuery();

}