Beginner Basics: Double Knitting
Each "stitch" actually consists of two stitches, a knit and a purl, one on each side of the fabric. The stitches alternate on the needles, but after they are worked, they separate into the front and back of a two-layer project.
1. Start by casting on with both colors held together. Slip the first stitch of the next row.
2. Holding both strands in the back of your work, knit the white stitch with the white yarn.
3. Move both strands to the front.
4. Holding both strands in front of your work, purl the red stitch with the red yarn. Repeat, always moving both strands to the front or back, then working a stitch with the appropriate color.