I haven't been knitting long myself, and I was having problems until I really figured out the difference between knit and purl. (I'm sure that sounds stupid, but there I was.) I finally noticed that when the stitch comes off the needle when I Knit, the bump goes to the back of the work. When I purl, the bump goes to the front of the work. If I'm knitting and bring the yarn in between the needles to the front, but continue to knit, it adds a stitch. (It also adds a little hole. When you do this on purpose, it's called a yarn over YO.) You can get the same effect if you are doing purl stitches and you bring the yarn in between the needles to the back and continue to purl. (Then it's called a yarn back YB) In both cases you get an extra stitch. Sometimes a pattern will counter balance the additional stitch by knitting or purling two other stitches together.
Keep trying. You will get the hang of it.