Hey there! This is my design for the challenge. A kids’ playground is the only thing that hit my mind. 
However I know that there are no shadows because I am using a background image. Although I tried to put a plane that will only receive shadows, I couldn’t make it invisible…
Try “Shadow Catcher” with Cycles!
Under the object properties:
The problem might be lining up the garden floor with the shadows though, but that’s another story that involves the camera settings… never done it.
Edit: If you already done like this, maybe the problem is the brightness of the background, you can increase the your main light source strength so it overcomes the brigtness of the environment and the shadows become visible.(if you don’t have a light source, add one)
Michael covers compositing (adding items to photos) near the end of the course (atm Section 15: Bonus: VFX and CGI 2.7x)
This will be explained in the upcoming lessons. It involves Post processing.
Fun playground, well done!
hmmmmm
thx, I just tried what you said. Well, it caught the shadows but it didn’t show what’s behind it (Transparent). Like it cropped the photo. I wanted the perspective to stay the same. Thanks anyway for your efforts. 
Thanks. I am loving this course.
Great! Glad you liked it!
