Describe some shadows. If there is the slightest bit of light, there will be shadows.
Some shadows are dark. Some are faint. The more you look for them, the more shadows you see.
Look for colors in the shadows. What are their shapes?
Write about the kinds of things you can see if you only pay attention to shadows.
Illustrate your work if you like.
Give your page a title. Sign and date it, too.