The six sided triangle blocks are put together in rows of half hexagons. Since you have already sewn your hexagons you can go several ways. Unsew the center seam and put them together in rows(you will need to pin to reduce the stretch on the bias edges) OR stitch them together with the dreaded Y seams OR add triangles to the 4 angled corners to make a square. You could also appliqué them to a square of fabric and then sew the squares together.