Help with a pattern

Working on a baby sweater. Im at the part where you divide body and arms. After you put some stitches on hold, it says to cast on 5 stitches. Not sure how to do this and where to put the cast on stitches. Do you just cast 5 new stitches onto the left needle? Then continue with the pattern?

Often you can take the needle with the working yarn coming off the tip in your left hand and cable or knit cast on the sts that you need. Then you would proceed with the pattern. What pattern are you doing? Can you give us a link to it or to a picture? Top down?

Yes, its seamless and knitted from the neck down. This is section i’m now:
Work 2 (2,2,4) rows even, removing stitch markers.
On the next RS Row, divide body and arms as
follows: k23 (25,25,27), put next 33 (35,36,37) sts
on hold on waste yarn, cast on 5 (5,7,7) sts, k47
(49,51,55), put next 33 (35,36,37) sts on hold using
waste yarn, cast on 5 (5,7,7) sts, knit to end. [103
(109,115,123) sts]
C

Yes, you’re casting on under the arms. After you knit across the 23 (25,25,27) sts and put the next sts on the holder, switch the needle from you right to your left hand and cast on, then continue across the bach and repeat the sleeve stitches onto holder and armhole cast on directions as given. There are directions for the knit or cable cast ons which work well here on the Free Videos tab at the top of the page under Cast Ons.
Sounds like a lovely baby sweater with very little seaming.