How do I cast on in the middle of a row.....row 5 pattern states to bind off 2 stitches. Row 6 states to cast on 2 sts. when I get to the bound off stitches.?

Knit into the next stitch and instead of pulling the old loop off, twist the new loop back on to the first needle just as you would when casting on originally. Do this twice then continue knitting as usual. You will have made a hole in the fabric.