In the back row are crocheted points the chains as long as needed for the buttonhole. The needle is then stung on the next point. That is, if you have work three chains stitches jump , three chains stitches and stung on the next stitch. On the next row, the stitches that were skipped in the previous row are crocheted.
At the height you want to make buttonhole, work is divided into two parts. And it will continue, weaving separately, first hand, until you reach the desired height of the buttonhole. Then it will continue weaving on the other hand was pending, considering the rows to resume tissue. Given the height of the buttonhole, weaving continues normally.