With black yarn pick up 21sts along the edge of block 6 (inc the black edge) and 21sts along the edge of block 7 (42sts)
Knit 4 rows if you have picked up from L-R and 5 rows if you have picked up from R-L
Abbrevations
Tw2 – knit into the front of second stitch on left needle, then knit into the front of the 1st stitch and slip both stitches off the needle together.
Pattern
Row 1 - *p1,K1* repeat *-* until the end of the row
Row 2 - *p2,K1* repeat *-* until the end of the row
Row 3 - *p1,tw2* repeat *-* until the end of the row
Row 4 - as row 2
Repeat rows 1 - 4 3time in all
Change to black and knit 4 rows
Cast off