To workt the quilt stitch:
Start by inserting the RH needle under the long strand:
Then insert the RH needle into the first stitch on the LH needle:
Now knit as if this were just a regular knit stitch, but pulling the yarn loop up through both stitches:
Slip both loops off the LH needle so that you have a new knit stitch on the RH needle and the strand is now behind your work and forming a V-shape.