Help with Scarf!!!!

[daisy151]

Hi Everyone! I am trying to knit this scarf for my mom and have run into some confusion! What is the difference b/w SL1 and PSSO?? I have looked everywhere on the internet and cannot find much about PSSO. And last question, what does it mean on Row 2 & 4 (WS)..Do I flip the needles or witch hands or just continue doing what I'm doing?? Thank you for any help!!! I posted the instructions below as well as the link.
http://www.jimmybeanswool.com/freeKn...oSilkScarf.asp
Finished Measurements: 6 1/2 x 86 inches

Materials
1 ball of Colinette Parisienne in 163 Vincent's Apron
2 balls of Colinette Tao Silk in 163 Vincent's Apron
Straight knitting needles, US size 9
Gauge
Not super important...

Abbreviations
rs: Right Side
ws: Wrong Side
K: knit
P: purl
K2TOG: knit 2 stitches together, as if they were one.
PSSO: pass slipped stitch over.
YO: yarn-over

Directions:
Holding 1 strand each of the Tao Silk and the Parisienne together, CO 28 sts

Row 1(rs): K2, *K3, YO, SL 1, K2TOG, PSSO, YO; repeat from * to last 2 sts, K2
Row 2 & 4 (ws): Purl
Row 3: K2, *YO, SL 1, K2TOG, PSSO, YO, K3; repeat from * to last 2 sts, K2
Repeat rows 1-4 until scarf measures about 85 inches unblocked (or until you only have enough yarn for 1 more row). BO all stitches.

[salmonmac]

Slip one means to pass the stitch unworked from the left needle to the right needle. PSSO means to pass slipped stitch over. So in