OK, I'm assuming that the "pattern 2tog 0 times" or "0 rows" are for your size and that you've left out the directions for the other sizes? If so, you can ignore them and the instructions simplify to:
Next Row (this is probably the right side, RS): patt 15, patt2tog, turn as if you were at the end of the row, leave rem 18 sts on a stitch holder.
You just want to work with the 16sts now.Working on these 16 sts only proceed as follows:-
Next Row (the wrong side WS). Patt.
Work 6 rows: (RS)dec1 st at neck edge in next and every foll alt row. This means work across the RS row to the neck edge, turn, (WS)decrease one st (you can bind off one or work 2 sts together) and work across the rest of the row. Work the next RS row, turn, decrease again on the WS row, work to the end, work the RS row, turn, decrease on the WS row and work to the end. Now you've finished the 6 rows and you're ready to work on a RS row for the next instructions