Cable stitch on a purl row?
 

Oh this butter tank is now giving me a head ache. I know what c6f means. slipp the first 3 stitches purl wise, knit the next 3, return the 1st 3 to needle and knit, what if I am cabling on a purl row? Do I then do the opposite, slip stitches knit wise, purl the next 3 then slip stitches back and purl those?

On a knit row, slip 3 to the front, the cable leans left. On a purl row, do the same thing, slip 3 to the front purlwise, purl 3, purl 3 from cable needle and the cable seen from the knit side will lean left..

You only cable on a knit row. On the purl side, you will generally knit the knits and purl the purls. It helps if you can tell which are which. Knit stitches look like little V's and purl stitches look like the turtle neck on a turtle neck sweater. Cabling isn't that hard. You're only doing it every fourth or sixth row or whatever, depending on your cable directions specified amount. The rest of the rows are all straight knitting, so you do need to know what the stitches look like. It beats having to count or be chained to the pattern if you can just eyeball it.