Inc 1 st question

I am very new to knitting and I would like to knit a Barbie dress. An snip of the pattern goes like this:

Next: Purl across
work in st st for 6 rows
Next: inc 1 st in every fourth st across
Next: purl across
Work in st st for 6 rows
Next: inc 1 st in every fifth st across

I am confused about the inc st. Do I do this in the 6th row of the st st? Or is it a seperate row?

Any help is appreciated!

ABOUT INCREASES:
Let’s say you have 21 stitches on the needle.
[COLOR=Blue]This row (in blue above) would go like this:
KKK[COLOR=Red]K[/COLOR] KKK[COLOR=Red]K[/COLOR] KKK[COLOR=Red]K [/COLOR]KKK[COLOR=Red]K[/COLOR] KKK[COLOR=Red]K[/COLOR] K
(the red[COLOR=Red] K[/COLOR] designates a [U]4th[/U] knit that you will work an increase into prolly using the K1fb, which means K1 in front and back of the stitch, creating 2 stitches out of 1 stitch)

[COLOR=DarkGreen]This row (in green above) would go like this:[/COLOR]
[COLOR=DarkGreen]KKKK[/COLOR][COLOR=Red]K[/COLOR] [COLOR=DarkGreen]KKKK[/COLOR][COLOR=Red]K[/COLOR] [COLOR=DarkGreen]KKKK[/COLOR][COLOR=Red]K[/COLOR] [COLOR=DarkGreen]KKKK[/COLOR][COLOR=Red]K[/COLOR] [COLOR=DarkGreen]KKK[COLOR=Red]K[/COLOR] K[/COLOR]
[/COLOR][COLOR=DarkGreen](the red K designates a [U]5th[/U] knit that you will work an increase into prolly using the K1fb, which means K1 in front and back of the stitch, creating 2 stitches out of 1 stitch)[/COLOR]

Of course, after each inc row, your stitch counts increase.
[COLOR=Blue]20+5=26
[COLOR=DarkGreen]26+5=31

[COLOR=Black][B]NOTE:[/B][/COLOR]
[COLOR=Purple][B]"[/B][/COLOR][/COLOR][/COLOR][COLOR=Purple][B]work in st st for 6 rows" means: after the “purl across” row, you will work 6 plain st st rows, with no increasing whatsoever. [/B][/COLOR]
[COLOR=Blue]

[/COLOR]

If you work 6 rows then inc on the next one, that’s the 7th row. Which would be a knit row after the 6 rows of stockinette st.

Thanks guys! You helped a lot! Got it!
Happy knitting!! :slight_smile: