The first thing you have to realize is that when you knit a stitch on the front, you're also creating a purl on the back. There is really only on stitch in knitting--it just depends on what side of it you're doing, if that makes sense.
If you knit every row, you're creating garter stitch, where you end up with alternate knit/purl rows showing on both sides. This will also happen if you purl every row.
In order to get stockinette stitch--where all the knit stitches are on one side and all the purl stitches are on the other side, you need to knit one row and purl one row.