The next stage is probably the easiest, as all you are doing is creating 4 rectangles. Start by picking up 9 sts along the edge of the right triangle just completed. You are picking up only 9 sts because you already have one stitch from the previous section. If you are changing colours for this section, join the new colour on the first of these 9 stitches and leave the 1 stitch in the previous colour. This will not be noticeable once you complete the next row or two.
Turn so that the wrong side is facing.
Slip 1, P9. Turn. K9, ssk. Turn.
Repeat this step 9 times.
Slip 1, P9. Turn. K9, ssk.
For the next rectangle pick up 10sts along the edge of the rectangle from the first row of rectangles
then follow the steps above until you have all four rectangles complete! Now you can really start to see the woven effect!
Once you have completed this second row of rectangles, alternate between the pattern for the first row of rectangles and the second row of rectangles until you reach your desired length ending with a first row of rectangles. The final step is the finishing triangles!