code: public void addCounterColumn(ByteBuffer name, long value) throws IOException
      {
          addColumn(new BufferCounterCell(metadata.comparator.cellFromByteBuffer(name),
                                          CounterContext.instance().createGlobal(counterid, 1L, value),
                                          System.currentTimeMillis()));
      }
docs: Insert a new counter column to the current row (and super column if applicable).
  @param name the column name
  @param value the value of the counter