Help Translating EZ Bootie Pattern

As a fairly new knitter, I humbly admit that I need a little handholding as I am trying to finish a pair of Elizabeth Zimmerman booties for my niece. Does anyone have any experience with these? The pattern is in her “Opinionated Knitter” book on page 108 I think. Can anyone tell me what she means by “K to centre” toward the end? Any help would be so appreciated!

Another question. When she says complete 4 more ridges, that means 2 rows of knitting per ridge for 8 more knit rows, right?