Draw the area you want to fill with stitches. You can also fill in a shape you have outlined with back stitch or something.
Ok, these are some stitches I prepared in advance. Bring your needle up from the back and then down again on the other side of your design.
Bring up your needle as close to where you pushed it down, but not so close that you risk pulling it through the fabric. Then down again on the other side of the design.
This is the back, where you can hopefully tell what is going on; the actual stitching is going on on the back of the fabric.
Ok, I hope I've managed to make this make some kind of sense. You can space the stitches wider apart for an even more