essentially what happens is this:
ssk, k, k, yo, sl 1 pwise, yo, k, k, k2tog
you do ssk= 1 decrease, 1 stitch less.
you knit 2 stitches.
you do a yo as described = 1 increase, 1 stitch more
you slip one stitch purl wise
you do another yo as described = 1 increase, 1 stitch more
then you knit 2
then you knit 2 together = 1 decrease, 1 stitch less.
so 2 times one less, 2 times one more = the same amount of stitches again
the yo produce "holes" in the fabric.
the increase and decrease in different spots of the piece (as here) create "tilting stitches" - sections of your knitting that do not run straight up but diagonal.
the fabric produced by that will be lacey and decorated.
and it WILL feel lose with the slipped stitch in between 2 yo, but that is allright, really. it will tighten up as you work more rows. I am positive that on the next row you will work the yo in knit or purl and they will just leave that desired hole and that is that.
what have you been trying?