Diana, I think you DID add a shadow to that top right flower, but you might have rearranged the layers so the flower was moved above the papers, but not the shadow. I think I see some shadow on its edge, so you didn’t forget it.
If you want to post an image that has some transparency on the outside, you can always save it as a jpg, which will add a white background for you, or you can save it as a png which will keep the transparency. That burlap is fine to, but in case you don’t want to add a background, that would be the way to go.
For the next project, if you follow closer to the instructions, at least for one “run”, you will see how the tools are working and how the layers are arranged. Then, you can run with your own interpretation of it. And if you get stuck, you know where we are!