To make a stitch when knitting, knit in the front and back loops of the same existing stitch, or make one knit stitch between the two existing stitches. The former method forms a bump on the pattern, whereas the latter method leaves an eyelet.
To make the usual knit stitch in the front and back loops of an existing stitch, first knit to the place where the stitch is to be introduced. Then, push the right needle in the front loop of an existing stitch, position the yarn around the needle, and pull through the gap. While you are pulling, the loop should become slightly elongated.
Do not transfer the stitch to the left needle. Instead, push the tip of the right needle into the stitch's loop located behind the needle. Make a knit stitch again. Take the stitch out of the left-side needle.
To make a stitch between two existing stitches without forming an eyelet, push the left needle under the yarn between the two stitches in the front-to-back direction, twist the stitch, and then make a knit stitch. Alternatively, insert the left needle into the yarn between the two stitches from behind, and knit using the front loop.
If you are working with purl stitches, make purl stitches in place of knit stitches when using either of the above methods.