You only need one ball of the main yarn, but
you will need two strands of it, so either work
from the center and outside of the same ball or
wind off part of a ball to use as your second
strand.

The puffed look of the garter stitches come from
stranding two yarns across the work, similar to
fair-isle knitting. Unlike fair-isle knitting, the
desired look here is achieved by pulling the floats
(the strands that run behind the work) as
TIGHTLY as possible.

This is a variation of what is sometimes called
corrugated ribbing or cartridge ribbing. Although,
both of those terms are also used for many other
kinds of two-strand (or even one-strand) ribbing.

The website that previously hosted this has dropped all of my old patterns. They are currently unavailable, but I may reissue them at another time.