I think you will be working the heel on needle one. So, on needle 2, slip 4 stitches onto needle 1, making 12 for the heel. Then, on needle 3 slip 2 stitches back onto needle 2. I hope this isn't confusing. You should now have 12 sts on one, 6 on needle 2, and 6 on needle 3. Hope this helps!
OTN: nothing :(