How to cast on in the middle of a row

[Usfgirl86]

Hello. I'm currently knitting stitch nation's lady glovelets and I have come across an instruction that I'm not familiar with.

Thumb hole(right side): work in in pattern as established, work 22 sts, bind off 2 sts, work to end of row (got this part)
Next row (wrong side): work to bind off sts Of previous row, cast on 2 sts, work to end of row


I have searched the web for information on how to cast on stitches in the middle of a row and have turned up nothing. If anyone can provide an explanation that would be awesome!

[suzeeq]

Cast on to the R needle with a backward loop, or move the needle to the L hand, do a knit CO, then back to the right hand to finish the round.