Following button-neck instructions - help!

Hi, I’m new here. Am working on my first project, a sweater for my nephew. I’ve done the back and almost finished the front, but am stuck at the instructions for shaping the neck. It does up at the side with 3 buttons.

The pattern says “pattern 21 stitches, turn. Cont on these 21 stitches. Decrease one stitch at neck edge in every following alt row until 15 stitches remain. Work 3 rows. Note: this side of neck has 6 rows less to accommodate shoulder opening”

I’ve knitted the 21 stitches and turned, but now what?! I tried to continue knitting on the 21 stitches, but it just finished the row to the same length and looked wrong…I can’t tell where the neck is supposed to appear.

And where is the ‘neck edge’?

Thanks for your help,

The neck edge is where you turned, I think. You would knit the 21 sts, turn, dec a st and finish the row. Then turn and knit across, turn and dec again. I think. Which pattern is it?