Do the instructions stay to cast off 3 stitches at the beginning of each row until you have 3 stitches left on needle? If so, you would bind off (same thing as cast off) the first three stitches of the row, then k or p to the end of the row. Then, on your next row, do the same thing. If it's a purl row, then purl two stitches and slip the first stich you purled over the second stitch (the one nearest the tip of the needle), then purl one more, slip the stitch furtherest away from the tip of the needle over the stitch closest to the tip of the needle, and do this one more time...then purl to the end of the row. Next row, assuming it's a knit row...knit two, bring the first stitch knitted over the stitch closest to the tip....etc. Do this until you only have 3 stitches left, then knit those 3 together, cut your yarn about 6 inches or so and pull it through that last stitch, and you're done!