Amy, it is good to see you having a go as it is the best way to learn. The three things that effect depth of field are the aperture, focal length and distance to the subject. With aperture say F1.8 ( the aperture is opened up very wide), has a very shallow depth of field where as all the way down to say F16 (the aperture is closed down to a small opening) has a very deep depth of field. May I suggest that you set up a subject as you have already done and take a series of shots with the only variation being various F stops and see what they look like. All the best with it.
Check your camera to see if it is in single shot mode, it may be in multiple shot mode. single shot will show a single square box and multiple shot will show three boxes super-imposed on each other. unsure check your camera manual or you tube.
Well looking at the code you attached it 3 times, not sure what happened but that's an easy fix if you click edit and remove two of them. I actually like the choice of F stop as the whole plant is basically in focus but the step behind and the items on it fall out of focus quick so it does that well, if you would have went any wider open it would have been overdone and the plant would have started going out of focus, (you can see that starting on some of the leaves. Was this for an assignment for class? If it is, here are a few critiques I would have that are good takeaways. Composition: While the items on the steps were likely intentional to illustrate depth of focus they come off a bit unintentional compositionally. I also think the lamp fights a little for the subject. I realize it needed to be close for lighting, I would either crop out or introduce the lamp more intentionally into the composition. Lighting/Color: I also noticed you have cooler light coming from camera left and warm light from the lamp image right. Mixing color temperature is something you want to be quite intentional about, otherwise you could try using a white foam board or something like that to bounce the warm light back on the plant instead of the cooler light camera left.
