Help with Pattern

[KnuttyKnittyMe]

Hi I am new to knitting and I am knitting a cardigan for my friends baby thats due in February. I'm knitting the back and starting to shape the armholes. The basic 4 row pattern is1 knit row, 2 purl row, 3 knit 1 purl 1, 4 purl row and repeat all until a certain length. Then keeping pattern correct cast off 1 stitch at beginning of next 2 rows. Next row knit 2, slip 1, knit 1, pass slipped stitch over, pattern to last 4 stitches, knit 2 together, knit 2. All of which I've done. This is what I don't understand...

Next row purl. Keeping 4 row pattern correct, repeat the last 2 rows until 21 stitches remain finishing on a wrong side. Cast off.

Do I purl a complete row as normal or do i purl 2, slip 1, purl 1, pass slipped stitch over, pattern to last 4 stitches then purl 2 together, purl 2?

Then if keeping to the pattern it would be a row of knit 1, purl 1...do I incorporate the above again? As in knit 1, purl 1, slip 1, pass slipped stitch over, pattern to last 4 stitches then what do, do I knit 2 together or purl 2 together? I'm quite confused! Please help.

[salmonmac]

"Next row knit 2, slip 1, knit 1, pass slipped stitch over, pattern to last 4 stitches, knit 2 together, knit 2.
Next row purl."
It seems to me that these are the 2 rows that you should be repeating. I would put the decrease on row 1 (the knit row) or on row 3, (the k1, p1 row).
So purl rows 2 and 4 and do the decreases on 1 and 3.
I think you could do a k2tog or p2tog for the decreases on the k1, p1 row. See what you think looks best.