Need Help with Herringbone Pattern

I hope someone can help me here! I am knitting a neckwarmer with a herringbone pattern. The instructions indicate the following:

K1, Sl1, K1, psso but knit through back loop first; repeat to last stitch, K1.

Within the *, do I knit through the back loop of the slipped stitch or through the back loop of the knit stitch? Also, I attempted to knit though the back loop of a stitch on the right needle and it was very awkward to say the least.

Thank you in advance!

Lori

It looks like it meant to knit the k1 through the back loop and didn’t know the abreviation, then PSSO… try it!

Is it My So called scarf?