Now that you can knit a square, you'll want to know - how do I make my project wider? Let TECHknitting teach you one of the best tricks to "increasing", or creating extra stitches where there were none.
Slide 1. Knit until the place where you want to increase.
Slide 2. Take the stitch from the row immediately below your left hand stitch, and tug it onto the left hand needle.
Slide 3. Your left hand needle with both stitches on it.
Slide 4. Knit both those stitches as normal, and voila! An invisible addition of a stitch.
This is just one possible way to add stitches, but I like this one because it's not visible, unlike knit-front-back or yarn-over (other techniques). This technique leads to the stitches slanting ever so slightly left (this is unavoidable, don't worry)