Can you link to your pattern or give its name and where you got it? Always helpful.
I'm making an assumption that where it says "step" it means stitches.
Basically you'll be working on 24 sts as heel flap sts. Transferring the other remaining sts to another needle will get them out of your way. At this point you'll just be working back and forth on the heel sts.
This video isn't exactly what you're instructed to do but may give you a better idea of what's going on. http://www.youtube.com/watch?v=6CFBFLQOqSU
You can also check out other sock videos for an overview if that's what you need.