It is simple. Park the car on level ground for at least 20 minutes. Pull the stick out, wipe it down, and reinsert it. Pull it back out and recheck the level. No sexual innuendos intended. It should be fairly obvious, if not, repeat the above steps. If the oil level is clearly between the dots, do NOT add oil. If not, only add enough to get in that range. Overfilling can also cause engine damage.
That nifty thing called an Owners Manual also demonstrates how to do this, among many other things.
That nifty thing called an Owners Manual also demonstrates how to do this, among many other things.