c# programatically commit all transaction or rollback sql server

Hi to all,

i have the following sql transaction which i need to catch if an error occurs (as it has more than 1 insert)!? how can i do that - something like begin trans - do all db work - otherwise roll back

  using (SqlConnection conn = new SqlConnection("Data Source=sqlconnectionstring;"))
            {
                conn.Open();
                SqlCommand cmd = new SqlCommand("INSERT INTO Category values(@name,@des,@type); SELECT Scope_Identity()", conn);
                cmd.Parameters.AddWithValue("@name", "nametest");
                cmd.Parameters.AddWithValue("@des", "namedes");
                cmd.Parameters.AddWithValue("@type", "nametype");
                Object newId = cmd.ExecuteScalar();
                cmd = new SqlCommand("INSERT INTO Packages VALUES (@pname, @CarId, @typeofpck);", conn);
                cmd.Parameters.AddWithValue("@pname", "pnametest");
                cmd.Parameters.AddWithValue("@CarId", newId);
                cmd.Parameters.AddWithValue("@typeofpck", "Black");
                cmd.ExecuteNonQuery();
            }

Thanks....