rib3 cast off 1st in rib....?

[momlovestoknit]

using Love Knitting magazine from Barnes and Noble. working on a chunky jumper that is using a rib st pattern 2x2 then 6x2. Have done well so far but now I'm working on the front piece and I'm shaping the neck.
I dont understand what they mean by
rib 3 cast off 1st in rib, rib 2 cast off 1st in rib, rib 3

then on the 4th row then it does this again but its
rib 4 cast on 1st, rib 3 cast on 1st . work 2 rows more in rib cast off in rib
Please help making a baby gift made the hat that goes with the jumper but sweaters are hard to do when your first learning how to do themThanks in advance..

[salmonmac]

The instructions want you to work 3sts in the rib pattern (either knits or purls) cast off 1 stitch, work 2sts, cast off 1 stitch, work 3sts.
Cast off in rib means to work the 2sts that you need for the bind off according to the pattern columns of sts that you have been doing.
Same goes for the 4th row except you're casting on:
work 4 sts, cast on one, work 3sts, cast on one.
Just be sure to maintain the overall rib pattern. You may have decreased sts but follow the columns of sts (instead of 6x2 you may be onto 5x2 for a small area for example).