Need help BADLY with pattern

This is for a button band Pattern says

Rep last 2 rows until band, when slighty stretched, fits up Left Front for sewing in place as you work and ending with right side facing for next row. Bind off in ribbing.

So my question is how am i sewing this on? Am I sewing it as a go? If so HOW? Help please! :grrr:

Thanks.

You’d measure it as you go and when it looks like it’s long enough, BO, then sew it to the sweater. You’d probably use a mattress stitch then.

sue