I am trying to learn how to do one sock on two circulars. I understand how to put it on the needles and get started but I am having a dickens of a time trying to figure out how to do a purl stitch on the first two stitches of the needle with the yarn coming from the back needle. I have a total of 60 cast on stitches with 30 on each needle. I am doing a K2, P2 ribbing so I end the first needle with 2 knit sts which means I have to start the second or back needle with two purl sts and I cannot for the life of me figure out how to bring my yarn to the front and do the purl stitch. The yarn is coming off the last stitch on the back needle. Do I put my needle in the stitch first and then somehow bring the yarn in from there or do I have to do something with the yarn first and then put the needle in front of the first stitch or what? This is crazy as it should be so easy but I am ending up with two stitches on the needle when I do the first purl stitch. I know this has to be something very easy so why am I have such a hard time doing it.
Question on doing ribbing on two circulars
Move the yarn to the front between the two needles, just like you would if you were stitching with straights. Bring the working needle to the back of the working yarn and insert it into the stitch.
But you can’t do that with two needles facing the same direction like they are when you are using two circulars and one sock. They are facing the same direction. ???
Ah! I understand the problem now… you stitch with the loose end of the circular. With the needle that doesn’t have any stitches, not the one that already has stitches on it.
I understand how to do the stitches (the knit ones at least) with the other end of the same needle. But it’s how to bring the yarn from the back needle forward and do the purl stitch I don’t understand. After you have gone through one needle’s stitches, rotated the needles, and are ready to begin the front needle’s stitches. The very first two sts have to be purled and I cannot figure how or where to take the yarn from the back needle to the front and then do my purl. You can’t really take it between the needles that are facing the same direction unless you take it down through the middle of the two needles and back up under the front needle. It’s all confusing me.
Ok, if this is the first time using 2 circs I’d recommend moving your
sts around so that each needle starts with knit stitches so you don’t
need to worry about the purl at the start. If you just don’t want to
do that then what you would need to do is bring the yarn [I]under[/I] the front needle to get it into the front for a purl. Then you just insert
rh needle to do a purl and wrap your yarn as usual. Some people find that they get ladders when starting a needle with a purl so be sure
to pull it kind of tight.
hth,
Libbie 
I was also going to suggest moving your stitches around so both needes start with knit stitches. It won’t matter until you get to the heel flap that the stitch count is uneven on the 2 needles.
Or, since the needles are flexible cables, just hold the back needle and curve the flex around to the front & just below the front needle. It should now look more oriented how straight needles would be and more easily bring theyarn between the 2 needles for the purl stitch.