Help with how to understand this pattern

[jas]

This is the first time I've made something other then a scarf and I'm having trouble understanding part of the pattern. This is what it tells me to do:
a) knit 5, bind off 5 knit to the last 10, bind off 5, knit to end.
b) working all 3 sides at the same time work for 1.5 inches

I did part A and that worked out fine but when i go to do part B i dont get what i do with the string that goes between the first section and the second section, is it suppose to be there?

by the way its for a arm hole of a dog sweater.

thanks

[jas]

Thanks, what exactly does that mean?

i am super lost

[Jints]

Knit sts of section A,drop yarn, join new peice of yarn to sts of section B, (Just Loop yarn over needle and start knitting with it) knit sts of section B, drop yarn, join new yarn to section C. knit across.
Keep working each section separately, but at the same time, each with its own piece of yarn.
for small sections like this I usually wind off a few meters of yarn into separate little balls if I don't have any spare big balls.
Those loose ends will all be woven in later to secure them when sewing up sweater.