Now you basically do the exact same thing on the other side with the second needle. Knit across the remaining leg/cuff stitches, place another stitch marker (this would be the end of a needle if you were using double-points) and pick up stitches along this side of the heel flap.
Because the round typically ends at the middle back of the heel, knit half your heel stitches onto this needle. That will be the end of your round, and you should have half of the stitches on each needle.
Now you can begin your gusset decreases, working exactly the same as you were before. If you're using a pattern written for double-pointed needles, remember that the stitch markers indicate where the ends of the needles would be, so that's where your decreases go.
