Be sure to ask a grown up for help.
Find a big tree or rock to use as a support.
Gather materials from nearby - pinecones, twigs, leaves, grass, flowers, and pebbles.
Construct the front of your fairy house so it looks like the entrance to the tree or rock - you can add a door, a roof, decorations, tiny plants, flowers, a pathway, anything!
Take a photo and then leave it there for others to admire.