How efficient add row with columns to table?

[Andrzej]

I simple-client.cc is:
for (uint64_t i = 0; i < num_puts; i++)
      table->Put(*MakePut(Row(FLAGS_row, i)));
where
std::unique_ptr<Put> MakePut(const std::string &row) {
  auto put = std::make_unique<Put>(row);
  put->AddColumn("f", "q", row);
  return std::move(put);
}
But there are two problems:
1. In above example column "q" is row_key, but if I want add other 
column than row, I don't know on which row will be added.
2.How efficient add many columns?

In general case , how add :
row_key, column1, column2...column 10