Cast on in middle of row

Good afternoon,
I’m a relatively new knitter and have come across something in my current pattern that I haven’t seen before.
I’m knitting a moss stitch border down the right front of a cardy.
After 3 rows of moss stitch, I did another row where every 10 stitches I cast off 2 stitches (for buttonholes).
For the next row, when I get to the place where the 2 stitches were cast off, it now says to Cast on 2 sts - I’m just not sure how to cast on when I am in the middle of the row? Can I just increase 2 - guess I will get the same result which is to get 2 sts back into the row?
Would appreciate any help.
Regards,
Megan

You can inc 2 by doing a loop co, or just put your right needle into the left hand and doing a knit or cable co of 2, then moving the needle back to the right hand. Doing a CO instead of inc makes the hole larger so it will match the BO 2 and you can get the button through.

Just a little sugestion, try some swatches to see which one you like best. Some of these tend to leave holes in your knitting. I just hate it when I get the whole front done and the buttonholes are annoying. Another one to try is knitted cast on through the back loop, makes a firmer edge.