You are asking about two socks at the same time on 2 circs and it looks like the tutorials the other posts are pointing you to are just showing you how to knit a sock on 2 circs. There is a pattern on Knitty here:
that will show you how to cast on for a pair of top down socks on 2 circular needles. I tried it for my second pair of socks and got as far as turning the heel. When it came time to pick up the stitches for the heel gusset I simply could NOT figure it out and ended up ripping them out. I wasn't able to find a tutorial on how to do that anywhere and didn't have anyone to show me at the time. But that link above will surely get you started.
Now I do all my socks toe up on 2 circs, one at a time. I don't like 2 at a time because my skeins were always getting twisted up but someday I just might give it another go.